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ELEMENTS, 



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CHEMICAL PHILOSOPHY, 



AA^^MMMA^tW^^kA^ 



BT 

Sm HUMPHRY DAVT, LL. D. 

Sec. R. S. Prof. Chem. R. I. and B. A. M. R I. F. R. S. E. M. R. L A. 

Member of the Royal Academy of Stockholn ; of the Imperial Med. and 
Chir. Academy of St. Petersburg^; of the American Philosophical Society i 
and Honorary Member of the Societies of Diblin, Manchester^ the Phyucal 
Society of Edinburgh, and the Medical Society of London. 



PABT L VOL. I. 






4W«<l/«MfV^M^^V««^lii«M^<VW^MWV«A>W«^«AA^«A%<%^^ 



PHILADELPfflA, 

PUBLISHED BY BRVPPORD Acn> INSIO^r^ 

AND INSKEEr C^* BKADFORDj 
NEW-YORK. 

T. 49" G. Palmer, printers. 

181S. 



I 



. I 

• I 



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>iSi 



\ 



TO LADY DAVY. 



There is no individual to whom I can with so much 
propriety or so much pleasure dedicate this work as to you. 
The interest you have taken in the progress of it, has been 
a constant motive for my exertions ; and it was begun and 
. finished in a period of my life which, o^ving to you, has 
been the happiest. Regiird it as a pledge that I shall con- 
tinue to pursue Science with unabated ardour. Receive it 
as a proof of my ardent affection, which must be unaltera- 
ble, for it is foimded upon the admiration of your moral and 
intellectual qualities. 

H. DAVY. 



/ 



^ 






ADTERTISEMENT. 



In this work I have endeavoured, as far as it was in my 
power, to employ the nomenclature most in use amongst 
the chemists of the present day in Britain. In consequence 
of the progress of discovery, some of the names adopted 
from the French school of chemistry now imply erroneous 
ideas. In such cases I liave recurred as often as was pos- 
sible to the familiar names, or the old names. 

In adopting new names, I have been guided by the ne- 
cessity of the case ; and have applied them only to new sub- 
stances, or to substances the nature of which had been mis- 
understood, and which were confounded with other bodies 
diftering from them in dieir nature. 

I may perhaps be censured for having proposed to sig- 
nify the combinations of chlorine or oxymuriatic gas by 
simple terminations, connected with the name of the basis, 
such as ane and ana ; but these terminations will serve at 
least as symbols of tlie class, and in this way may assist the 
memory. 

In the last Bakerian lecture, published in die Philoso- 
phical Transactions, I have proposed to denominate the 
combinations of chlorine supposed to contain one propor- 
tion, by the termination aniy those supposed to contain two 
by awa, and those containing three by anie. As, however, 



VI ADVERTISEMENT, 

amongst the metallic combinations of chlorine, there are 
never more than two distinct combinations belonging to the 
same metal, I liave given the termination ane to the first, 
and that of ana to the second, without reference to propor- 
tions ; or where there has been only one, I have used sim- 
ply anc. If my original proposal should be adopted, it will 
however be easy to make the corrections, and the cases are 
very few that will require it. Common salt, which con- 
tains two proportions of chlorine, and which in this work is 
called sodane, will be called sodana ; ferrane will be called 
ferranea ; ferranea, ferranee ; and arsenicane must be chan- 
ged to arsenicana. 

Some persons may chuse rather to use the word clJoride, 
following the analogy of oxide ; but as I have expressed 
in the introduction, our nomcnclatui-c would have been 
more simple and useful without any attempt at theoretical 
expressions of the composition of bodies ; and as the fixed 
alkalies, earths, and oxides, are similar bodies, and the ter- 
mination a has been applied to the two first, it might be 
properly extended to the last. 

The word oxide is however now current, I have there- 
fore used it, and have employed Dr. Thomson's method 
of distinguishing the different oxides of the same metal, 
by prefixing to them syllables derived from the Greek nu- 
merals ; deutoxide, tritoxide, tetroxide, signify that the 
bodies contain two, three, or four proportions of oxygene. 
When tlie word oxide alone is used, one proportion only 
of oxygene is supposed to exist in it. 

Whatever pains be taken, it will not be possible to 
make the existing nomenclature conformable to the idiom 
of our language ; and till some general principles for its 
improvement are agreed to by the enlightened in difierent 



ADVERTISEMENT. VU 

parts of Furope, it cannot be expected to be even a philo- 
sophical language; and till a more simple system is adopt- 
ed, innovation will be censured sometimes perhaps even 
w^hen it is nercssiu-y, and neology generally brought for- 
ivard as a reproach. 

I have in a few instances only given an account of the 
experiments, from the results of which the numlxrs repre- 
senting tlie undecomposed bodies were calculated. 

To have given accurate histories of those cxix?riments, 
would have deen incompatible with the object of an elemen- 
tary book devoted to the general truths and methods of the 
science ; I shall however shortly present them to the pub- 
liC| in a work containing the details of labours that I have 
carried on during the last twelve years in analytical che- 
imstry. 

I have usually given whole numbers, taking away or 
adding fractional parts, that they may be more easily re- 
tained in the memory. When the number was gained from 
experiments in which a loss might be sui:)poscd, I have 
added fractional parts, so as to make a whole number. 
Thus the number representing barium, is nearer 129 than 
130; but it is given as 130, because it was deduced from 
an indirect experiment in which a loss of weight was more 
probable than an increase from any foreign source. 

In a future edition of this work, should my imj^rfcct 
kbours be favourably received, I may hope to be al)le to 
complete the series of numbers, and to fix some that are 
doubtful. 

I cannot conclude without acknowledging my obliga- 
tions to my brother Mr. John Davy, for the able assista:. :e 
he aflPorded me in the progress of the researches ^vhich form 
the foundation of this treatise. 



Yui ▲svEBTiSEmirr. 

I have likewise received much useful experimental aid 
from >Ir. E. Daw, and Mr. \V. Moore. 

The greater number of the experiments were made in the 
labomtorv of the Roval Institution ; and all that were fit- 
ted for demonstration have been exhibited in the theatre 
of that useful public establishment in my annual courses of 
lectures; and have been received bv the members in a 
manner which I shall always remember with gratitude. 

Bn'Mey Square^ 
June U 181:2. 



CONTENTS. 



Iktroduction Plage 1 

Historical View of the Progress of Chemistry 

PART I. 

ON THE LAWS OF CHEMICAL CHANGES: ON UNDECOU- 

POUNDED BODIES AND THEIR PRIMARY COMBINATIONS. 

33 

DIVISION 1. 

ON THE POWERS AND PROPERTIES OF MATTER, AND THE 
GENERAL LAWS OF CHEMICAL CHANGES. 

Preliminary Observations . , » 35 

Of the Forms of Matter .36 

Gravitation .... 37 

Cohesion . .38 

Of Heat, or calorific Repulsion . . 39 

On cliemical Attraction, and the Laws of Combination and Decomposition 54 
Of Electrical Attraction and Repulsion, and .their Relations to Chemical 

Changes . . . .70 

On Analysis and Synthesis : on the Circumstances to be atteiuled to in tliesc 

Operations, and on the Arrangement of undecompoundcd Bodies 101 

DIVISION II. 

OF RADIANT OR ETHEREAL MATTER. 

Of the Effects of radiant Matter, in producing the Phenomena of Vision 109 
Of the Operatioxj of radiant Matter in producing Heat 



y 



X CONTENTS. 

Of thn KObctii of rAcUunt Matter in producing chemical Changes 117 

Of tliv Nature of tjic Motioni or Affections of radiant Matter 119 

DIVISION III. 

OK KMPYKHAL UNDBCOMPOUMDED SUBSTANCES, OR UNDE- 
(HmVOUNUEl) SUBSTANCES THAT SUPPORT COMBUSTION, 
ANU TIlEtR COMBINATION WITH EACH OTHER* 

l»4N\rra\ Otiimatuiavi . 127 

UtVvi^iw i;m . .129 

CKK«i)^» vvr «x\>*taurtatk Gas • 1S3 

DIVISION IV- 

IM^ VNI>ttCOMPlHtK]>EII INFtJlMMABLE |^ JLCIDIFEROUS 
9VB»T<Xt^l($ \OT M«TAtJI.1C» .\KD TMEIB BOiTARY COM- 
BINATIUX$ WITH OXTCOSXE AND CHLORIXR, OR WITH 
lUCH OTHER* 

|^i^)evi^;ir»c Ksw^ xY vMbaMMftk Air i}, 

^$}«;^rdM»r IS* 

^V 1ftk'«9^»^n4i ... l£^ 

iavi$iQX V. 



H 
X 



>s>-* villi IlisJ 



4 



coirt&irrs 



Alaminam 

Giucinum 

Zirconum • 

Silicum • 

Ittrium 

Manganesum 

Zinc, or Zincum 

Tin, or Staimum 

Iron, or Ferrum 

Lead, or Plumbum 

Antimony, or Antimonium 

Biimuth, or Biamuthium 

Tellurium 

Cobak, or CobalUim 

Copper, Cuprum 

Nickel, or Nickolum 

Uranium 

Osmiun^ 

Tungsten, or Tung^tenum 

Titanium 

Columbium 

Cerium 

Palladium 

Iri^um 

Rhodium 

Mercury, or Mercurium 

Silver, or Argentum 

Gold, or Aurum 

Platinum 

Arsenic, or Arsenicum 

Molybdenum 

Chromium 



901 
203 
204 
305 
207 
208 
212 
215 
218 
223 
227 
229 
232 
233 
236 
239 
241 
242 
243 
244 
245 
246 
247 
248 
249 
250 
252 
254 
255 
257 
261 
263 



DIVISION VI. 

OF SOME SUBSTANCES THE NATURE OF WHICH IS NOT 

YET CERTAINLY KNOWN. 



Preliminary Observations 

Of the Fluoric Principle 

Of the amalgam procured from ammoniacid Compouiid« 



265 
ib. 



i 






Xir CONTENTS. 

DIVISION vn. 

ON THE ANALOGIES BETWEEN THE UNDECOHPOtJNBEB 
SUBSTANCES; SPECULATIONS RESPECTING THEIR NA- 
TURE; ON THE MODES OF SEPARATING THEM, AND 
ON THE RELATIONS OF THEIR COMPOUNDS* 

Of the* Analogies between the undecompounded Substances; Ideas respecting 
their\iature . . . 273 

Of the Analogies between the primary Coropoundsy and on their chemical Re- 
lations , . • . . 379 
On the relative AttiraoUons of the undecomposed Substances for each other 283 
On the Methods of separating the undecomposed Bodies from each other 285 
General Observations^ and Conclusion of Part First . . 286 



■'/•» 



INTRODUCTION. 



^OST of the substances belonging to our globe are constantly un- 
dergoing alterations in sensible qualities^ and one variety of matter 
becomes as it were transmuted into another. 

Such changes, whether natural or artificial, whether slowly or 
rapidly performed, are called chemical ; thus the gradual and almost 
imperceptible decay of the leaves and branches of a fallen tree ex* 
posed to the atmosphere, and the rapid combustion of wood in our 
fires, are both chemical operations. 

The object of Chemical Philosophy is to ascertain the causes of 
^1 phaenomena of this kind, and to discover the laws by which they 
are governed. 

The ends of this branch of knowledge are the applications of 
natural substances to new uses, for inctiaa^g the comforts and en- 
joyments of man, and the demonstration of the order, harmony, and 
intelligent design of the system of the earth. 

The foundations of chemical philosophy, are observation, experi- 
ment, and analogy. By observation, faciii are distinctly and minutely 
impressed on the mind. By analogy, similar facts are connected. By 
experiment, new facts are discovered ; and, in the progression of 
knowledge, observation, guided by analogy, leads to experiment, and 
analogy, confirmed by experiment, becomes scientific truth. 
: To give an instance. — Whoever will consider with attention the 
slender green vegetable filaments (Conferva rivularia) which in 
the summer exist in almost all streams, lakes, or pools, under the 
different circumstances of shade and sunshine, will discover glol^ujies 
of air upon the filaments exposed under water to the sun, but no air 
®n the filaments that are shaded. He \\\\\ find that the effect is 

roL. I. A 



2 INTBODUCTION. 

owing to the presence of light. This is an observation; but it gives 
no information respecting the nature of the air. Let a wine glass 
filled with water be inverted over the conferva, the air will collect in 
the upper part of the glass, and when the glass is filled with air, it 
may be closed by the hand, placed in its usual position, and an in- 
flamed taper introduced into it ; the taper will bum with more bril- 
liancy than in the atmosphere. This is an exfieriment. If the phe- 
nomena are reasoned upon, and the question is put, whether all 
vegetables of this kind, in fresh or in salt water, do not produce such 
air under like circumstances, the enqtirer is guided by analogy : and 
when this is determined to be the case by new trials, a general scien* 
tific truth is established— That all confervae in the sunshine produce 
a species of air that supports flame in a superior degree ; which has 
been shewn to be the case by various minute investigations. 

These principles of research, and combinations of methods, have 
been little applied, except in late times. A transient view of the pro- 
gress of chemical philosophy will prove that the most brilliant dis- 
coveries, and the happiest theoretical arrangements "belonging to it 
are of very recent origin ; and a few historical details and general ob-* 
servations upon the progress and effects of the science wUl forip^ 
perhaps, no improper introduction to the elements of this branch of • 
knowledge. *" • . 

The only processes which can be called chemical, khowhito the-. 
civilized nations of antiquity, belonged to certain arts, such as 'ttietal-' ' 
lurgy, dyeing, and the manufacture of glass or porcelain ; but thiese 
processes appear to have been independent of each other, pursued 
in the workshop alones aud unconnected with general knowk^gc* 

In the early mythological systems of the Egyptian prieatsj and 
tlie Bramins of Hindostan, some views respecting the chemical' 
changes of the elements seem to have been developed, which passed, • 
under new modifications, into the theories of the Greeks; but as th'e'f. 
most refined doctrines of this enlightened people, concerning natural '• 
causes, in their best times, were little more than a collection of vague f 
speculations, rather poetical than philosophical, it cannot well be • 
supposed that in earlier ages, and amongst nations less advanced in 
cultiv^on, there were any traces of genuine science. 

The inhabitants of Lower Egypt, where the overflowing of the 
Nile covered a sandy desert with vegetation and life, might easily 



INTRODUCTION, 3 

adopt the notion, that water, in different modifications, produced sjl 
the varieties of inanimate and organized matter ; and this dogma 
characterized the earliest school of Greece. 

To generalize upon the great forms or powers of nature, as ele- 
ments, requires only very superficial observation ; and hence the 
theories seem to have originated, wliich have been attributed to 
Ana^mander, and others of the eaHy Greek philosophers, concem- 
iog air, earth, water, and fire. 

As geometry and the mathematical sciences became improved, 
mechanical solutions of the changes of bodies were n^itural conse- 
quences, such as the atomic philosophy of the Ionian sect, and the 
five regular solids assumed by the Pythagoreans as the materials of 
the upi verse. 

In the beginning of the Macedonian dynasty, tlie school of Aristotle 

gave a transient attention to the objects of natural science, but the 

' '.^ greit founder attempted too many subjects to be able to offer correct 

•J views of any jwie series.^^ And his erroneous practice, thatofadvan- 

f cingVeeneral principles, and applying them to particular instances, so 

. •?. fiatal to' truth in all sciences, more particularly opposed itself to the 

n, X progress of one founded upon a minute examination of obscure and 

• . ; hidde^ properties of natural bodies. 

iphrastus, the successor of Aristotle, did not, it appears, adopt 

. ' "i^ th^ffMblime, though purely speculative doctrine of his master, the 

•''•"r* iiiliiEity of nfiatter, and its diversity of form*; — for he says, in the 

' %*•" ^?gwi°g of his book concerning fossils, * stones are produced from 

e eaiittt lAetals from waterf.' — How. such a notion as the last could 

\v«hattW)epn formed, it is difiicult to discover; yet, Theophrastus is 

• :f . petliiigs^ the best observer amongst the ancients, whose works are in 

i*. . our possession, and the theories of this distinguished teacher, who 
ff^ i&*f|aid ta have had a class of 2000 pupils, cannot be considered as an 
'••^*V,uiifav<)urahie specimen of the theoretical physics of the age, 

• •}\ .;>'eV«^J^iJ Vt i (pvo-tq hjcSqy rh re uhq %a) v v^u- Ar^totelis Natural. 

/. ' Auscult Lib. ii. 495, fol. Par. 1654. 

f«j$ ^£ Ai0iK rs %») %fru, M6m Vi^nrort^». Thqophrasti de LapidibuSt Lvg. 
Bat. 1613. 



4. IHTRODUCTION. 

In all pursuits which required only the native powers of the in- . . 
tellect, or the refinements of taste, the Greeks were pre-eminent ;— 
their literature, their works of art, offer models which have never 
been excelled. They possessed, as if instinctively, the perception 
of every thing beautiful, grand, and decorous. As philosophers, they 
^ed not from a want of genius, or even of application, but merely j 
because they pursued a false path,— because they reasoned more 
uiion an imaginary system of nature, than upon the visible and tangi- 
ble universe. 

It will be in vain to look in the annals of Rome for science, that 
did not exist in Greece. The conquerors became the pupils of the 
conquered; and the Romans did little more than clothe the systems 
of their masters in a new dress, and adapt them to a new p^btte- 

The grand, but unequal poem of Lucretius, contains the ^fis^riLct t',.' . 
of the opinions of Epicurus, compared with those of other cj^elinit-'! .-' 
e^ teachers. The Natural History of Pliny, is a coilectiqiC,^m ^ ;■. 
all sources, but principally from Theophrastus and AristotlelS Tlic • 
details from his own observation are more interesting when t^e^ re- ^,,.- 
lateto artiiicial, than when they refer to natural operations; the«^tjiV re- 
lative notions are of the rudest kind. The earlier philosgjiifioal t' . 
work of the Romans, as if indicative of the youth of tlic ponW^i i^ ( /.' 
marked by power and genius, by boldness and incorrectnq^^^c'.V ;' 
latter, as if it belonged to their old age, by garrulity, cppioSft^^ t- •, 
amuung anecdote, superstitious notions, and vulgar prejudiceki,^* V^i' 

Some of the historians of this science*, in theii- zeal forihaBM^iy"-.V,-' 
of its antiquity, have indeed endeavoured to find instances 

* Many of the akhemicsl writers derive atchemyfrom Tubal Cain-t oil 
Uetmes Trigmegignu, tbe Mercury of the Greeki. The Rral: wriling nKofioaltjr 

on achEmical gubject, is a manugcript supposed to be of the Erib centin^^^^Bosi 
mot, on the art of making gold and silver i which wu in the kul^E*]! 
Paiii. Suida«, who wrote in (he ninth or tenth cenlury, mcntlonB-IJiiji___, __ „ . . 
Iitving burnt the books of the Egypdans conceming the chemistry o^'eityer lin4 ''-'f^ 
gi^d: "irifi jffituiut itfyufa mil Xt'"'*'-" Le^i^o"' Tom. i. pag. is^i,' f '^''f■■^ 

For a minute investigation or the claims of the andents to chemical l^nov^lcog^, ■ * 
the reader may consult Borrichios de Ortu et Progress, Chim. Bergman. Opus. , ^ v- 
quia, vol, IV. de primordiis Chzm, and Lenglet Dufrenoy, Histoire de la Philoso- '^ - 
phie her'net'l'w 




INTRODUCTION, 5 

quaintance vriih some doctrines of practical chemistry, at least, 
amongst the ancients.— -Thus Democritus is quoted by Laertius as 
having employed himself in processes for imitating gems, and for 
softening and working ivory. Caligula is said to have made experi- 
ments with the view of extracting gold from orpiment. — Dioscoii- 
des, who is supposed to have been physician to the celebrated Cleo- 
patra, has described the process of subliming mercuiy from its ores. 
-—Even Cleopatra herself, on the evidence of such circumstances, 
might be considered as an experimenter, because, in the madness of 
profusion, she dissolved a pearl in vinegar, and made a nauseous 
draught of a costly and beautiful substance ; but it is idle to relate 
such circumstances as indications of science. If chemical operations 
had been known to any extent, beyond their mere relations to the 
arts, some mention of them might have been expected in the medi- 
cal writings of those times; but not even distillation is noticed in 
the works of Hippocrates or Galen ; and the same Dioscorides who 
has been just alluded to, and who probably possessed whatever 
knowledge was at that time extant in Egypt, recommends the use 
of a fleece of wool or a sponge, for collecting the products from boil- 
ing or burning substances*. 

The origin of chentiistry, as a science of experiment, cannot be 
dated farther back than the seventh or eighth century of the christian 
ci% and it seems to have been coeval with the shoit period in 
which cultivation and improvement were promoted by the Arabians, 

The early Mahometans endeavoured to destroy all the records of 
the former progress of the human mind ; and, as if to make com- 
pensation for this barbarian spirit, the same people were destined, 
in a more advanced period, to rekindle the light of letters, and to 
become the inventors and cultivators of a new science. 

The early nomenclature of chemistry demonstrates how much it 
owes to the Arabians.— The words alcohol, alkahest, aludel, alembic, 
alkali, require no comment. 

The first Arabian systematic works on chemistry are said to have 
been composed by Geber in the reigns of the caliphs Almainon and 
Almanzor. The preparation of medicines seems to have been the 

* Dioscpridis Uber U de pictno oleo, pag. 5^. 




6 INTRODUCTION. 

primary object iii this study; and Rhases, Avicenna, and Avenzoar, 
who have described various chemical operations in their works, 
Were the celebrated physicians of the age. 

Amongst a people of conquerors, disposed to sensuality and luxury 
even from the spirit of their religion, and romantic and magnificent 
in their views of power, it was not to be expected that any new know- 
ledge should be followed in a rational and philosophical manner; 
and the early chemical discoveries led to the pursuit of alchemy, the 
objects of which were to produce a substance capable of converting 
all other metals into gold ; and an universal remedy calculated in- 
definitely to prolong the period of human life. 

Reasonings upon the nature of the metals, and the composition of 
the philosopher's stone, form a principal part of the treatises ascribed 
to Gebcr* ; and the disciples of the school of Bagdat seem taha^ 
been the first professed alchemists. 

It required strong motives to induce men to pursue the tedious 
and disgusting processca of tho furnace ; but labourers could hardly^ 
be wanting, When prospects so brilliant and magnificent were offer- 
ed to them; the ipeans of procuring unbounded wealth ; of forming 
a paradise on eaith; and of enjoying an immortality depending on 
their o^vn powers. 

The processes supposed to relate to the transmutation of metals^ 
and the elixir of life, were probably first made known to the Euro- 
peans during the time of the crusades ; and many of the warriors who, 
animated with visionary- plans of conquest, fought the battles of 
their religion in the plains of Palestine, seemed to have returned to 
their native countries under the influence of a new delusion. 

* The library of the British Museum contains several works bearing the name of 
Oeber : amongst them are, De Alchemia aigentea, Specuhim Alchemise, et de In- 
ventione perfectionis : but they appear to be compilations formed by alchemists 
of the 15th and 16th centuries. Arsenic, mercury, and sulphur, are considered in 
them as elemeitts of the metals ; distillation is distinctly described. Alcohol, cor- 
rosive sublimate, and different saline combinations of iron, tin, copper, and lead, 
are mentioned in them ; but they abound in obscure descriptions of mysterious pro- 
cesses, and contain an account of some impracticable experiments. — ^The Liber 
l^omacum is the most intelligible part of the works ascribed to Geber ; it contsuns 
Bcription of several metallurgical operations, and of the common a^qparatus of 
saycr. 



INTRODUCTION. 7 

The public spirit in the west was calculated to assist the progress 
of all pursuits that carried with them an air of mysticism. Warm 
with the ardor of an extending and exalted religion, men were much 
more disposed to believe than to reason;— the love of knowledge 
and power is instinctive in the human mind ; in darkness it desires 
light) and follows it with enthusiasm even when appearing merely in 
delusive glimmerings. 

The records of the middle ages contain a g^reat variety of anec- 
dotes relating to the transmutation of metals, and the views or pre- 
tensions of persons considered as adepts in alchemy : these early 
periods constitute what may be regarded as the heroic or fabulous 
ages of chemistry. Some of the alchemists were IdW impostors, 
w;hose object was to delude the credulous and the ignorant; others 
seemed to have deceived themselves with vain hopes ; but all follow- 
ed the pursuit as a secret and mysterious study. The processes 
were communicated only to chosen disciples, and being veiled in the 
most enigmatic and obscure language, their importance was enhan- 
ced by the concealment. In all timca men arc governed more by 
what they desire or fear, than by what they know ; and in this age it 
was peculiarly easy to deceive, but difficult to enlighten, the public 
mind ; truths were discovered, but they were blended with the false 
and the marvellous ; and another era was required to separate them 
from absurdities, and to demcmstrate their importance and uses. 

Amald of Villa Nova, who is said to have died in 1250, was one 
of the earliest European enquirers who attended to .chemical opera- 
tions. In the editioti of the works ascribed to him, published at Ley- 
den in 1509*, there ai'e several treatises on alchemical subjects, 
which shew that he firmly believed in the transmutation of metals ; 
the same opinions are attributed to him and to Geber ; and he seems 
to have followed the study with no other views than those of prepar- 
ing medicines, and attempting the composition of the philosopher's 
stone. 

Raymund Lully of Majorca is said to have been a disciple of Ar- 
nald, and applied himself much more than his instructor to philoso- 
phy ; but the works on general science, ascribed to him, are more 

* Opera Amaldi de Villa Nova, fol. 1509. 



8 INTRODUCTION. 

abundant in abstract metaphysical propositions, than in facts; he 
followed, in his physical views, the plan of Aristotle, and our opinion 
of his chemical talents cannot be very exalted, if the alchemical 
treatises bearing his name be regarded as genuine documents. 

Amald and Lully are both celebrated by the vindicators of alche* 
my, as having been certainly possessed of the secret of transmuta- 
tion. Amald is said to have converted iron into gold at Rome ; and it 
is pretended that Lully performed a similar operation before Edward 
I. in London, of whicli gold nobles were said to have been made*. 

That the delusions of alchemy were ardently pursued at this time 
may be learnt from a reference to the public acts of these periods. 
Pope John the 22d, who was raised to the pontificate in the year 
1316, openly condemned the alchemists as impostors, and the bull 
begins by stating, that " they promise what they do not perform ;'* 
and in England an act of Parliament was passed in the fifth year of 
the reign of Henry IV, prohibiting the attempts at transmutation, 
and making them feloniousf. 

Even in these times, howovor, Uiere were-aoFine few efforts to form 
scientific views. In the beginning of the thirteenth century, Roger 
Bacon of Oxford applied himself to experiment, and his works offer 
proofs of talents, industry, and sagacity. He was a man of a truly 
philosophical turn, desirous of investigating nature, and of extending 
the resources of art, and his enquiries offered some very extraordina- 
ry combinations; but neither his labours, nor those of Albert of 
Cologne, his contemporary, who appears to have been a genius of a 
kindred character, had any considerable influence on the improvement 
of their age. The wonders performed by . the experimental art 
%vere attributed by the vulgar to magic ; and at a time when know- 
ledge belonged only to the cloister, any new philosophy was of 
course regarded even by the learned with a jealous eye. 

It would be a labour of little profit to dwell upon the works of the 
professed alchemists of the fourteenth and fifteenth centuries, of 

• Bergman. Opu&cula, Tom. IV. pag. 126. 

t Lord Coke calls this act the shortest he ever met with. 5 H. IV. Statutes at 
large, Vol. I. page 457. " None from henceforth shall use to multiply gold or sil« 
ver, or use the craft of multiplication, and if any the same do, he shall incur the. 
pain of felony.'* 



INTRODUCTION. 9 

Richard and Ripley ih England, Isac in Holland, Pico of Mirandnla 
and KofFsky in Poland. The works attributed to these persons are 
of a similar stamp*, and contain nothing which can either instruct 
or amuse an intelligent reader. Basil Valentine of Erfurt deserves 
to be separated from the rest of the enquirers of this age, on account 
of the novelty and variety of his experiments on metallic prepara- 
tions, particularly antimony : in his Currua triumfi/uilis AntimonU he 
has described a number of the combinations of this metal. He used 
the mineral acids for solutions, and seems to have been one of the 
first persons who observed the production of ether from alcohol. He 
flourished about the year 1413. 

Cornelius Agp4ppa, who was bom at Cologne in 1486, openly pro- 
fessed magic, and endeavoured to connect together judicial astrolog^^ 
the hermetic art, and metaphysical philosophy ; and he was followed 
by Paracelsus, in Switzerland, and Digby, Kelly, and Dee, in 
England. 

The first Arabian alchemists seem to have adopted the idea, that 
the elements were under the dotninioii of spiritual beings, who 
might be submitted to human power ; and the notions of fairies and 
of genii, which have been depicted with so much vividness of fancy 
and liveliness of description in the Thousand and One Nights, seem 
to have been connected with the pursuit of the science of transmuta« 
tion, and the production of the elixir of life. The speculative ideas 
of the Arabians were more or less adopted by their European dis- 
ciples. The Rosicrucian philosophy, in which gnomes, sylphs, sala- 
manders, and nymphs were the spiritual agents, supposed capable of 
being governed or enslaved by mto, seems to have originated with 
the alchemists of this period ; and Agprippa, Paracelsus, and their 
followers, above mentioned, all professed to believe in supernatural 
powers, in an art above experiment, in a system of knowledge not 
derived from the senses. It would be a tedious and useless task, to 
describe all the absurdities in the opinions and practices of this 
school. Paracelsus alone deserves particular notice, from the cir- 
cumstance of his being the first public lecturer on chemistry In 

* Among;st them arc Ricardi Angli Libellus, ^f^i ^ijiAgta^, OpQS Sstnrni 
johan. Isac. Compounde of Alchemy by George Ripley. 
VOL, r. R 




10 INTHOOUCTIOK. 

Europe^ and &om the more hnportast circumstance o£ his applica- 
tion of mercuriai preparations to the cure of cfLseases. The magis- 
trates of Basle established a professor's chair for their couDtrrniaii^ 
but he soon quitted an occupation in which regularitf was necessary, 
and spent his days in wandering firom place to place, searching' fery 
and reyealing secrets. He pretended to confer immortalitj by Ids 
medicines, and yet died at the z^e of 49, at Saltsburg^ in the year 
1541*. 

The enthusiasm of this man almost supplied his want of genius^ 
He formed a number of new preparations of the metals, which were 
studied and applied by his disciples; his exaggerated censuFQ.ef the 
methods of the ancients, and of the systems of his day, had an effect 
in dimini^iiag their popularity ; one error was expelled by another ; 
and it is a great step towards improYement, that men should know 
^ey have been in delusion. 

Van Helmont, of Brussels, bom in 1588t, was formed in the 
school of alchemy, and his mind was tinctured with its prejudices : 
but his Tiewa conccming nature and the elements were distinguished 
by much more plulosophical acuteness, and more sagacity, than those 
of any former writer. He b the first person who seems to have had 
any idea respecting elastic fluids, different from the air of the atmo- 
sphere ; and he has distinctly mentioned three of these substances^ to 
which he applied the term gases : namely, aqueous gas or steam, 
unctuous or inflammable gas, and gas from wood or carbonic acid 
gas. Van Helmont developed some accurate views respecting the 
permanent elasticity of air, and the operation of heat upon it ; and a 
sketch of a curious instrument >'ery similar to the differential ther- 
mometer, is to be found in his worksf . 

Van Helmont has used a term not so applicable or intelligible as 
gas, namely, bias ; which he supposed to be an influence derived 
from the heavenly bodies, of a most subdle and etherial nature ; and 
on the idea of its operations in our terrestial system, he has endea^ 
voured to found the vindication of astrology |f. 

* Dicdonnaire Historique, par Moreri, tome vilL pag. 54. 
t Ibid, torn. V. pag. 570. 

I Johaa Baptist. Van Helmont, Opera Omniai 4to. pag. 61. article Acr. 
I! Ibid, pag. 114. 



INTRODUCTION. 11 

At this period there was no taste in the public mind to restrain 
vague imaginations. There were no severe critics to correct the 
wanderings of genius. The systems of logic, adopted in the schools^ 
were founded rather upon the analogies of words, tlian upon the re- 
lations of things ; and they were more calculated to conceal error, 
than to discover truth. — Till the revival of literature in Europe, 
there was no attempt at philosophical discussion in any of the sciences; 
the diffusion of letters gradually brought the opinions of men to the 
standard of nature and truth; failures in the experimental arts pro- 
duced caution, and the detection of imposture created rational 
scepticism. 

The delusions of alchemy were exposed by Guibert, Gasscndi, 
and Kepler. Libavius answered Guibert in a tone which demon- 
strated the weakness of his cause. This person, who died in 1616, 
was the last active experimentalist who believed that transmutation 
had actually been performed; and in the beginning of the 17th cen- 
tury the processes of rational chemistry were pursued by a number 
of enlightened persons in diiferent parts of Europe. 

A metallurgical school had before this time been founded in Ger- 
many. George Agricola published, in 1542, his twelve books, de 
Re Metallica^ or, on the methods of extracting and purifying the 
useful metals; and he was followed by Lazarus Erckeni, assay- 
master general of the empire of Germany, whose works, brought 
;^ forward in 1574, contain a number of useful practices detailed in a 
simple and perspicuous manner. 

Lord Bacon happily described the alchemists as similar to those 
Jiusbandmen who, in searching for a treasure supposed to be hidden 
in their land, by turning up and pulverising the soil, rendered it 
fertile ; in seeking for brilliant impossibilities, they sometimes dis- 
covered useful realities ; and in speaking of the chemistry of his 
time, he says, a new philosophy has arisen from the furnaces, which 
has confounded all the reasonings of the ancients. This illustrious 
man himself pointed out many important objects of chemical en- 
quiry ; but hp was a still greater benefactor to the science, by his de- 
velopement of the general system for improving natural knowledge. 
Till his time there had been no distinct views concerning the art of 
experiment and observation. Lord Bacon demonstrated how little 



s 



12 IKTBODUCTIOK. 

could be effected by the unassisted human powers, aiiid the weak- 
ness of the strongest intellect even without artificial resources. He 
directed the attention of enquirei*s to instruments for assisting the 
seQses> and for examining^ bodies under new relations. He taught 
that Man was but the servant and interpreter of Nature ; capable of 
discovering truth in no other way but by observing and imitating 
her operations : that facts were to be collected and not speculations 
fornted : and that the materials for the fbundatioos of true systems 
of knowledge were to be discovered, not in the books of the ancients, 
iu>t u\ metaphysical theories^ not in the £uicies of men, but in the 
visible and tangible external world. 

Though Van Helmont had formed some just notions respecting 
the properties of air, yet his views were blended with obscure and 
vague speculations, and it is to the disciples of GaUikeo, that the 
true knowledge of the mechanical qualities and agencies of elastic 
ihiids is owing. After Torricelli andP^iscal had shewn the pressure 
and weight of the atmosphere, the investigation of it» effects in 
chemical operations became an obvious problem. 

John Rev is genei*ally quoted as the first pei*soD who shewed by 
experiments that air is fixed in bodies during calcination : but it ap- 
pears from the work of this acute and learned man> that he reason- 
ed upon the processes of others^ rather than upou his own obser- 
vations. 

Uc quotes Fachsius, Libavius> Cesaipin> and Cardan, as having as- 
certained the increase of weight of Lead during its conven^on into a 
calx*^ and he mentions an experiment of |-Iammeru» Poppius, who 
found that antimony culcined by a burning-glass, notwithstanding the 
loss of vapours, yet was heavier after the process* 

Rey ridicules the various notions of tiie alchemists on the cause 
uf this phacnomenon ; and ascTibes it to the union of aii* with the 
metal; he supposes that air is miscible with other bodies besides 
metals, and states distinctly that it may be expelled from water. 

The observations of John Rey seem to have excited no attention 
.-inongst his cotemporaries. The philosophical spii4t was only be- 

" Sur !a Recherche de la caiue par laiiueile £staia ei \t PkomU ^utgrmsiKCju de 
t^imis inand on le& caicine. A Bazsa» 1630. 



INTKODUCTION. 13 

ginning to animate chemistry, and the labourers in this science, oc- 
cupied by their own peculiar processes, were little disposed to listen 
to the I'easonings of an enquirer in general science ; yet, though the 
most active of the forms of matter were neglected in the processes 
of the operative chemists of this day, and consequently no just views 
formed by them, still they discovered a number of important facts 
respecting the combinations and agencies of soUd and fluid bodies. 
Glauber, at Amsterdam, about 1640, made &nown several neutral 
salts, and several compounds of metallic andiregetablc substances* 
Kunckel, in Saxony and Sweden, pursued technical chemistry with 
very great success, and was the first person who made any philor 
sophical experiments upon phosphorus, which was accidentally dis- 
covered by Brandt in 1669*. Bamer in Poland, and Glaser in France, 
published elementary books on the science, and Borichius in Den- 
mark, Bohn at Leipzic, and Hoffman at Halle pursued specific 
scientific investigations with much zeal and success ; and Hoffman 
was the first person who attempted the philosophical analysis of 
mineral waters. 

About the middle of this century likewise mathematical and 
physical investigations were pursued in every part of the civilized 
world with an enthusiasm before unknown. The new mode of improv- 
ing knowledge by collecting facts, associated together a number of 
labourers in the same pursuit. It was felt that the whole of nature 
was yet to be investigated, that there were disdnct subjects connected 
. with utility and glory, sufficient to employ all enquirers, yet tending 
to the common end of promoting the progress of the human mind. 
Learned bodies were formed in Italy, England,, and France, for the 
purpose of the interchange of opinions, the combination of labour 
and division of expense in performing new experiments, and the ac- 
cumulation and diffusion of knowledge. 

The Academy del Cimento was established in 1651, under the 
patronage of tihe Duke of Tuscany ; the Royal Society of London, 
in 1660 ; the Royal Academy of Sciences of Paris, in 1666. And a 
number of celebrated men, who have been the great luminaries of 
the different departments of science, were brought together or 

• Homberg, Mem, Acad. Paris, torn, x. pag. 58. ^ 



14 INTRODUCTION. 

formed in these noble establishments. The ardour of scientific in- 
vestigation was excited and kept alive by sym]pathy : taste was im- 
proved by discussion, and by a comparison of opinions. The con- 
viction that useful discoveries would be appreciated and rewarded, 
was a constant stimulus to industry, and eveiy field of enquiry was 
open for the free and unbiassed exercise of the powers of genius. 

Boyle, Hookc, and Slare, were the principal early chemical in- 
vestigators attached to the Royal Society of London. Homberg, 
Geoff'roy, and the tji^, Lemerys, a few years later, distinguished 
themselves in France. 

Otto de Guericke of Magdeburgh invented the air pump ; and 
tliis instrument, improved by Boyle and Hooke, was made an im- 
portant apparatus for investigating the properties of air. Boyle* and 
Hookef, from their experiments, concluded that air was absolutely 
necessary to combustion and respiration, and tliat one part of it only 
was employed in these processes. And Hooke formed the saga-. 
cious conclusion, that this principle n the same as the substance 
fixed in nitre, and that combustion is a chemical process, the solu- 
tion of the burning body in elastic fiuid, or its union vnth this 
matter. 

Mayow of Oxford, in 1674, published his treatises on the nitro- 
aerial spirit, in which he advanced opinions similar to those of Boyle 
and Hooke, and supported them by a number of original and curious 
experiments^ ; but his work, though marked by strong ingenuity, 
abounds in vague hypotheses. He attempted to apply the imper- 
fect chemistry of his day to physiology ; his failure was complete, 
but it was the failure of^a man of genius. 

Boyle was one of the most active experimenters, and certainly the 
greatest chemist of his age. He introduced the use of tests or re- 
agents, active substances for detecting the presence of other bodies ; 
he overturned tlie ideas which at that time were prevalent, that the 

* Boyle's Works, vol. iv. page 90. 

t Hookers Micographia, page 45, 104, 105. 

I Tract, p. 28. He has particularly assigned the cause of the calcination of 
metals, « Quippe vix concipi potest unde augmentum illud antimonii nisi a par* 
ticulis nitro acreis igneisque inter calciniindum fixis proced^t." 



INTHODUCTIOK. 15 

resuHs of operktions by fire were the real elements of things, and 
he ascertained a number of important facts respecting inflammable 
bodies, acids, alkalies, and the phsenomena of combination ; but nei- 
ther he nor any of his contemporaries endeavoured to account for 
the changes of bodies by any fixed principles. The solutions of the 
phsenomena were attempted either on rude mechanical notions, or 
by occult qualities, or peculiar subtile spirita or ethers supposed to 
exist in the different bodies. And it is to the same great genius, 
who developed the laws that regulate the motions of the heavenly 
bodies, that chemistry owes the first distinct philosophical elucida- 
tions of the powers which produce the changes and apparent trans- 
mutations of the substances belonging to the earth. 

Sugar dissolves in water, alkalies unite with acids, metals dissolve 
in acids. Is not this, says Newton, on account of an attraction be- 
tween their particles ? Copper dissolved in aquafortis is thrown down 
by iron. Is not this because the particles of the iron have a stronger 
attraction for the particles of the acid than those of copper ; and do 
not different bodies attract each other with different degrees of 
force* ? 

A few years after Newton had brought forward these sagacious 
views, the elder Gcpffroy endeavoured to ascertain the relative at- 
tractive powers of bodies for each other, and to arrange them in an 
order in which these forces, which he named affinities, were ex- 
pressedf. 

Chemistry had scarcely begun to assume the form of a science, 
when the attention of the most powerful minds were directed to 
otlier objects of research ; the same great man who bestowed on it 
its first accurate principles, in some measure impeded its immedi- 
ate progress by his more important discoveries in optics, mechanics, 
and astronomy. 

These objects of the Newtonian philosophy were calculated by 
their grandeur, their simplicity, and their importance, to become th« 
study of the men of most distinguished talents; the effect that they 
occasioned on the scientific mind may be compared to that which 
tlie new sensations of vision produce on the blind receiving sight ; 

* Newton's Works, quarto, torn. iy. pag? 242. 
t M^mobts dc rAcadcmic, 1718, page 256. 



Id isTnonncTioK. 

they awakened the highest interest* the most cnihusiastic admira- 
tion, and. for neariy half a century, absoH^ed the attemicHi of the most 
eminent phWoHophers of Britain and France. 

Germany still continued the great school of practical chemistry. 
and at this period it gained an ascendancy of no mean character over 
the rest of Europe in the philosophy of the science. Becchcr, who 
Tras bom at Spires in 1645* after having studied with minute atten- 
tion the operations of metallurgy, and the phaenomenaof the minexal 
kingdom, formed the lyild idea of explaining the whole ^tcm of 
the earth by the mutual agency and changes of a few elements. x\iid 
hy supposing the existence of a vhrifiable, a metallic, and an inflaai- 
mable earth, he attempted to account for the vanons productioBS of 
rocks, crystalline bocdes, and metallic veins* aaguming a continued 
interchange of principles between the atmosphere, the ocesm^ and 
the solid surface of the globe, and considering the operations of ubh^ 
ture as all capable of being imitated by art. 

The Phfjgica 9ubtrrranea^ and die Oedi/ius chemictM of this author 
are very extraordinary productions. They display the efforts of a 
vigorous mind, tlie conceptions of a most fertile imagination, but tiw 
conclusions are too rapidly formed ; there is a want of logical preci- 
sion in his reasonings; the objects he attempted were grand, tml 
his means of execution comparatively feeble. He endeavoured to 
raise a perfect and lasting edifice upon foundations too weaky from 
materials too scanty, and not sufficiently solid ; and the work, thou^ 
magnificent in design, was rude^ unfinished, and feeble, and rapidly 
fell into decay. 

Beccher added very little to the collection of chemical experi- 
ments, but he improved the instruments of research, simplified the 
manipulations, and, by the novelty and boldness of his speculadbiw, 
excited inquiry among his disciples. 

His most flistinguiahed follower was George Ernest Stahl, bom 
in 1 6^10, who soon attained a reputation superior to tliat of his mas- 
ter, and developed doctrines which for nearly a century constituted 
^hc theory of chemistry of the whole of Europe. 

Mhertus Magnus had advanced the idea that the metals were 
canhy substances impregnated with a certain inflammable principle. 
Beccher supported Uie idea of this principle, not only as the cause 



INTRODUCTION, 17 

of metallization, but likewise of combustibility ; and Stahl endea- 
voured, by a number of ingenious and elaborate experiments, to 
prove the existence of phlogiston, as it was called, and to explain its 
agencies in the phasnomena of nature and art. 

Glauber, about fifty years before Stahl began his labours, had dis- 
t:overed the combination of fossil alkali and sulphuric acid, which 
still bears his name. And Stahl, in operating upon this body, thought 
he had discovered the proof, that the inflammability not only of me- 
tals, but likewise of all other substances, was owing to the same 
principle. Charcoal is entirely dissipated or consumed in combus- 
tion ; therefore, says this philosopher, it must be phlogiston nearly 
pure : by heating charcoal with metallic earths, they become me- 
tals ; therefore they are compounds of metallic earths and phlogiston : 
by heating Glauber's salt, which consists of sulphuric acid and fosul 
alkali, with charcoal, a compound of sulphur and alkali is obtained ; 
therefore sulphur is an acid combined with phlogiston. Stahl en- 
tirely neglected the chemical influence of air on these phenomena ; 
and though Boyle had proved that phosphorus and sulphur would 
not bum without sdr, and had stated that sulphur was contained in 
sulphuric acid, and not the acid in sulphur, yet the ideas of the 
Prussian school were received without controversy. Similar opi- 
nions were adopted in France by Romberg and GeofFroy, who as- 
sumed them without reference to the views of the Prussian philoso- 
fhevy and opposed them to the more correct and sagacious views of 
the English school of chemistry. 

Though misled in his general notions, few men have done more 
than Stahl for the progress of chemical science. His processes 
were, many of them, of the most beautiful and satis&ctory kind ; 
he discovered a number of properties of the caustic alkalies and 
metallic calces, and the nature of sulphureous acid ; he reasoned 
upon all the operations of chemistry in which gaseous bodies were 
not concerned, with admirable precision. He gave an axiomatic 
form to the science, banishing from it vague details, circumlocu- 
tions, and enigmatic descriptions, in wliich even Beccher had too 
much indulged ; he laboured in the spirit of the Baconian school, 
multiplying instances, and cautiously making inductions, and appeal- 

c 



18 INTRODUCTION. 

h^ in all cases to experiments which, though not of the most refined 
kind, were more perfect than any which preceded them. 

Dr. Hales, about 1724, resumed the investigations commenced 
with so much success by Boyle, Hooke, and Mayow; and en- 
deavoured to ascertain the chemical relations of air to other sab- 
stances, and to ascertain by statical experiments the cases in nature^ 
in which it is absorbed or emitted. He obtained a number of im- 
portant and curious results ; but, misled by the notion of one ele- 
mentary principle constituting elastic matter, and modified in its 
properties by the effluvia of solid or fluid bodies, he formed few in- 
ferences connected with the refined philosophy of the subject: he 
disengaged, however, elastic fluids from a number of substances, 
and drew the conclusion that air was a chemical element in many 
compound bodies, and that flame resulted from the action and re- 
action of xrial and sulphurous particles*. 

In 1756 Dr. Black published his admirable researches on calcare- 
ous, magnesian, and alkaline substances, by which he proved the 
existence of a gaseous body, perfectly distinct from the air of the 
atmosphere. He shewed that quicklime differed from mart>le and 
chalk by containing this substance, and that it was a weak acid, ca- 
pable of being expelled from alkaline and earthy substances by strcmg 
acidsf. 

Ideas so new and important as those of the British philosopher, 
were not received without opposition ; several German enquirers 
endeavoured to controvert them. Meyer attempted to shew that 
limestones became caustic, not by the emission of elastic matter, but 
by combining with a peculiar substance in the fire ; but the loss of 
weight was perfectly inconsistent with this view : and Bergman at 
Upsal, Macbride in Ireland, Keir at Birmingham, and Cavendish 
in London, demonstrated the correctness of the opinions of Black ; 
and a few years were sufficient to establish his theory upon immuta- 
ble foundations. 

. The knowledge of one elastic fluid different from air, immediately 
led to the enquiry whether there might not be others. The pro- 

■ « 
; • yales' Statical Essays, 2d cd. 8vo. vol. I pag. 315. 

t Assays and Observations Physical ai\d Literary, vol. ii. page 159. 



INTRODUCTION. 19 

cesses of fermentation which had been observed by the ancient 
chemists, and those by which Hales had disengaged and collected 
elastic substances, were q^w regarded mider a novel point of view ; 
and the consequence was, that a number of new bodies, possessed 
of very extraordinary properties, were discovered. 

Mr. Cavendish, about 1765, invented an apparatus for examining 
elastic fluids confined by water, which has been since called the hy- 
dro-pneumatic apparatus. He discovered inflammable air, and 
described its properties ; he ascertained the relative weights of 
fixed air, inflammable air, and common air, and made a number 
of beautiful and accurate experiments on the properties of these 
elastic substances. 

Dr. Priestley, in 1771, entered the same interesting path of en- 
quiry; and, principally by repeating the processes of Hales, added « 
number of most important facts to this department of chemical phi- 
losophy. He discovered nitrous air, nitrous oxide, and dephlogisti- 
cated air ; and by substituting mercury for water in the pneumatic 
apparatus, ascertained the existence of several triform substances, 
which are rapidly absorbable by water, muriatic acid air, sulphur- 
ous acid air, and ammonia. 

Whilst a new branch of the science was making this rapid pro- 
gress in Britain, the chemistry of solid and fluid substances waa 
pursued with considerable zeal and success in France and Germany; 
and Macquer, Rouelle, Margrafi*, and Pott, added considerably to 
the knowledge of fossile bodies, and the properties of the metals. 
Bergman, in Sweden, developed refined ideas on the powers of 
chemical attraction, and reasoned in a happy spirit of generalization 
on many of the new phaenomena of the science ; and in the same 
country Scheele, independently of Priestley, discovered several of 
the same aeriform substances: he ascertained the composition of the 
atmosphere ; he brought to light fluoric acid, prussic acid, and the 
substance which has been improperly called oxymuriatic gas. 

Black, Cavendish, Priestley, and Scheele, were undoubtedly the 
greatest chemical discoverers of the eighteenth century ; and their 
meiits are distinct, peculiar, and of the most exalted kind. Black 
made a smaller number of original experiments than either of the 
other philosophers ; but being the first labourer in this new depart- 



20 LNTRODUGTIOK. 

ment of the science, he had greater difficulties to overcome. Hia 
methods are distinguished for their simplicity, his reasonings are 
admirable for their precision; and his modest, clear, and un- 
affected manner, is well calculated to impress upon the mind a con- 
viction of the accuracy of his processes, and the truth and candour 
of his narrations. 

Cavendish was possessed of a minute knowledge of most of the 
departments of natural philosophy : he carried into his chemical re- 
searches a delicacy and precision, which have never been exceeded : 
possessing depth and extent of mathematical knowledge, he reason- 
ed with the caution of a geometer upon the results of his experi- 
ments : and it may be said of him, what, perhaps, can scarcely be 
said of any other person, that whatever he accomplished, was per- 
fect at the moment of its production. His processes were all of a 
finished nature ; executed by the hand of a master, they required 
no correction ; the accuracy and beauty of his earliest labours even, 
have remained unimpaired amidst the progress of discovery, and 
their merits have been illustrated by discussion, and exalted by 
time. 

Dr. Priestley began his career of discovery without any general 
knowledge of chemistry, and with a very imperfect apparatus. His 
characteristics were ardent zeal and the most unwearied industry. 
He exposed all the substances he could procure to chemical ag^- 
cies, and brought forward his results as they occurred, without at- 
tempting logical method or scientific arrangement. His hypotheses 
were usually founded upon a few loose analogies; but he changed 
them with facility ; and being framed without much effort, they were 
relinquished with little regret. He possessed in the highest degree 
ingenuousness and the love of truth. His manipulations, though 
never veiy refined, were always simple, and often ingenious. 
Chemistry owes to him some of her most important instruments of 
research, and many of her most useful combinations; and no 
Hngle person ever discovered so many new and curious substances. 

Scheele possessed in the highest degree the faculty of invention ; 
all his labours were instituted with an object in view, and after happy 
or bold analogies. He owed little to fortune or to accidental cir- 
cumstances 2 bom in an obscure situation, occupied in the duties of 



k 



INTRODUCTIOK*. 31 

an irksome employment, nothing could damp the ardour of his 
mind or chill the fire of his genius : with very small means he ac- 
complished very great things. No difficulties deterred him from 
submitting his ideas to the test of experiment. Occasionally misled 
in his views, in consequence of the imperfection of his apparatus, or 
the in&nt state of the enquiry, he never hesitated to give up hia 
opinions the moment they were contradicted by facts. He was 
eminently endowed with that candour which is characteristic of 
great minds, and which induces them to rejoice as well in the de- 
tection of their own errors, as in the discovery of truth. His papers 
are admirable models of the manner in which experimental research 
ought to be pursued ; and they contain details on some of the most 
important and brilliant phenomena of chemical philosophy. 

The discovery of the g^ses, of a new class of bodies, more ac- 
tive than any others in most of the phaenomena of nature and art, 
could not fail to modify the whole theory of chemistry. The an- 
cient doctrines were revised ; new modifications of them were 
formed by some philosophers ; whilst others discarded entirely all 
the former hypotheses, and endeavoured to establish new generali- 
zations. 

The idea of a peculiar principle of inflammability was so firmly 
established in the chemical schools, that even the knowledge of the 
composition of the atmosphere for a long while was not supposed 
to interfere with it ; and the part of the atmosphere which is absorb- 
ed by bodies in burning, was conceived to owe its powers to its at- 
traction for phlogiston. 

All the modem chemists who made experiments upon combus- 
tion, found that bodies increased in weight by burning, and that 
there was no loss of ponderable matter. It was necessary there- 
fore to suppose, contrary to the ideas of Stahl, that phlogiston was 
not emitted in combustion, but that it remained in the inflammable 
body ader absorbing gaseous matter from the air. But what is 
phlogiston? was a question constantly agitated. Inflammable air 
had been obtained during the dissolution of certain metals, and 
during the distillation of a number of combustible bodies. This 
light and subtile matter, therefore, was fixed upon as the principle 
of inflammability; and Cavendish, Kirwan, Priestley, and Font&na, 
were the illustrious advocates of thb veiy ingenious hyi)ot jk 



2i ijrrKODrcTio:» 

ir. iTi4' liayen' wicwt:. ui*; imTLur cdtivcticc. mto a 
««rti.> u* Uk aiJhurpiiuii o: ai:. cuui:. u-. rt"-7^c.. wiinout tfie 
o: 'ait) iiiitbLiiiinaui'. suiiSiuiiLt: au: n'Jiic-. ir. conciuoec.. thu that 
was no iii:Lchsii> lu* suppobiiiv ui. 'JLJS!t:i:c:. c- an^' pccnlin 
pK oi uilldiiiiiibijuin - r. aLxuuniin. w ui cainmaxioi. of 
lilt buujeci. iiean^ auuu: Ui-. sanii- uim Mm- uuLcii uii mv 
M'uo hac. iKci- iu' huiu'. uiiK eir^uvrcw i: rciYcann; tnt e: 
of XUL UiJiibi |>iiiiua(>piirr^ Luvt'i icnut.'. n. opiiuai. 
Uk iittiuii o: Uiv Ui' prtiuuccc: irun: ui-. '^u.: c nicrcur; 
Ail i?T:. sii«:wrc uia i: y^n^ u:. ai' vii::*: sunuonr:. xmmf. 
rauuii lifUc: inan uoniiuui. a:: v iuwi: ii- ::iit'nYiirar namec* 
tUL baiut bULibiaitL*. Uiu. ^iit:^'.!'." ail. :?ciiet;i'. naw. procured 
titiicr liitruiili'. biiubuuikt:: lu'. \ t:::' iJLiort. aii^ na. oarui 

LavOibit:* ciibtuvri-eu liia: uk SLini'. cj* i: uraaucec 
Vi\iijcaliui' o liifialii'. Laiici u* Ciiu.:';;u.^ a.- ihl- xrxixcr. i& 
iiuiiii^' iii« (.aiuiiauui u: iiuiebiuiK- iitrii.-. n-. conciuoec*. tiiat ttk 
eiabli' 1jui< j* LOUiiKJbcc o: ox\)rriK siii: ciiiircoa. . aiu trrar. tk 

f^a*. •^iiLi.iCC AiJtt ti««. cuutiMibiuo: o '..irs- t«-:jE:aiirt;s.. 

Ilia* «!»»;; »^a»c: ai"« •^ULiO-jiiyr- ',.■ ^\ if*/. hvLiar aix ~< 

«bb>ji;«i.: Vti y-j.f' *y *..** r. .;' .-v.. '.':.• ■•"r: it ;ra^- gur 

4*v 'y y7i....f.^ '... >^.. J • . -r ■ »- -'jrii'JbsiIuit nocrc, 

■ ■ 



/ 



INTHODUCTION. 23 

logic, extent of view, and sagacity of induction. His discoveries were 
few, but he reasoned with extraordinary correctness upon the labours 
of others. He introduced weight and measure, and strict accuracy of 
manipulation into all chemical processes. His mind was unbiassed 
* by prejudice ; his combinations were of the most philosophical na- 
ture ; and in his investigations upon ponderable substances, he has 
entered the true path of experiment with cautious steps, following 
just analogies, and measuring hypotheses by their simple relations 
to facts. 

The doctrine of Lavoisier, soon after it was framed, received some 
important confirmations from the two grand discovenes of Mr. Ca- 
vendish, respecting the composition of water, and nitric acid; and 
■ the elaborate and beautiful investigations of Bertliollet respecting 
the nature of ammonia ; in which phenomena, before anomalous, 
;. were shewn to depend upon combinations of aeriform matter. 

The notion of phlogiston was, however, defended for nearly 20 
: years, by some philosophers in Germany, Sweden, Britain, and Ire- 
- land. Mr. Cavendish, in 1784, drew a parallel between the hypo- 
. thesis, that all inflammable bodies contain inflammable air, and the 
doctrine in which they are considered as simple substances, in a 
, paper equally remarkable for the precision of the views displayed 
. in it, and for the accuracy and minuteness of the experiments it con- 
tains. To this great man, the assumption of M. Lavoisier, of the 
^ matter of heat, appeared more hypothetical than that of a principle 
of inflammability. He states, that the phaenomena may be explained 
. on either doctrine; but he prefers the earlier view, as accounting, 
, in a happier manner, for some of the operations of nature. 

De Morveau, Berthollet, and Fourcroy, in France, and William 
Higgina and Dr. Hope, in Britain, were the first advocates for the 
antiphlogistic chemistry. Sooner or later, that doctrine which is an 
expression of £Eicts must prevail over that which is an expression of 
opinion. The most important part of the theory of Lavoisier was 
merely an arrangement of the facts relating to the combinations of 
oxygene : the principle of reasoning which the French school pro- 
fessed to adopt was, that every body which was not yet decompound- 
ed, should be considered as simple ; and though mistakes were made 
Vfiih respect to the results of experiments on the nature of bodies, 




24 BrraoDircnos. 

yet this logical and tniiT pfaikisophiaLL principie was not Tiolattd; 
and the aystemadc manner in which it was enforced* wa» of the 
p'eateat use in pronutin^ the piogreaa of the science. 

Till 1 786* there had been no attempt to reform the nomcnclatare 
of chemiatiT ; the names applied by diacoTerers to the 
which they made known were still employed. Some of these 
which originated amongst the alchemiata* were of the moat faurfaar- 
ous kind; few of them were sii£Bciently defoiite or preciae, aad 
most of them were founded upon hjoae anzifogiesy. or upon folae tteiH 
retical views. 

It was felt by many philosophers* particulariy by the ifluBtnans 
Bergman* that an improvement in chemical nomencianire was bc- 
cessary, and in 1737, Messs. Lavoisier, Morveau. BerthDUet, aad 
FourcToy presented to the world a plan for ai almost endre change 
in the denomination of chemical subamnces* fomided upon the idea 
of calling smple bodies by some names cisaracteristic of tfaair most 
striking q^ualides« and of naming cooipauiid bodies foam the "J^^w**-** 
which composed them. 

The new nomenriamre was speedily adopted in France ; mder 
some mnffificarions it was received in Germanv : and after *"*"*^ 
discusson and oppoBtioiu it became the laniniage of a new aad 
rising i^eneratian of chemists in England. It materiallT assisted the 
cfiffbaion of the antiphlogistic doctrine, and even jociiixated tiic ge- 
neral acquiation of the science ; and many of its demils were ca» 
trived with much address, and were worthv of its celebrated war 

m 

tfaors ; but a very digfat fcfer ei icc to the philosophical principles «f 
language will evince diat its foundations were imperfect* and that 
the plan adopted was not calculated for a progressive branch of 
knowledge. 

Simplicity and preciaion ou^it to be the characteristics of a scioH 
tific nomenclature ; words should sgnify things, or the analogies of 
things, and not opimons. If all the elements were certainly knowiH 
the principle adopted by Lavoisier would have possessed an admicft- 
ble application : but a substance* in one age supposed to be simple^ 
in mother is prnved ?q be compound ; and -cicrf irerw. A theoretical 
nomenclanire is Liable to continued alters^ns ; Qjru^enaied muriaac 
•md is a^ improper a name as defthiogiscicared ytmrine acid. Every 



INTRODUCTION. 25 

school believes itself in the right ; ami if ever}' school assumes to 
itself the liberty of altering tlie names of chemical substances, in 
consequence of new ideas of their composition, or decomposition, 
there can be no permanency in the language of the science, it must 
always be confused and uncertain. Bodies which are similar to each 
other should always be classed together; and there is a presumption 
that their composition is analogous. Metals, earths, alkalies, are 
appropriate names for the bodies they represent, and independent of 
all speculative views ; whereas oxides, sulphurcts, and muriates arc 
terms founded upon opinions of the composition of bodies, some of 
which have been already found erroneous. Th.^ least dangcixtus 
mode of giving a systematic form to a language seems to be, to sig- 
nify the analogies of substances by some common sign afRxed to the 
beginning or the termination of the word. Thus, as the metals have 
been distinguished by a termination in um, as aurum^ so their calci- 
form or oxidated state might have been denoted by a termination in 
a, as aura ; and no progress, however great, in the science, could 
render it necessary that such a mode of appellation should be 
changed. Moreover, the principle of a composite nomenclature 
must always be very limited. It is scarcely possible to represent 
bodies consisting of five or six elements in this way, and yet it is in 
such difficult cases that a name implying a chemical truth would be 
most useful. 

The new doctrines of chemistry, before 1795, were embraced by 
almost all the active experimental enquirers in Europe ; and the 
adoption of a precise mode of reasoning, and more refined forms of 
experiment, led not only to the discovery of new substances, but 
likewise to a more accurate acquaintance with the properties and 
composition of bodies that had long been known. 

New investigations were instituted with respect to all the produc- 
tions of nature, and the immense variety of substances in tlie mine- 
ral, vegetable, and animal kingdom, submitted to chemical experi- 
ments. 

The analysis of mineral bodies, first attempted by Pott in experi- 
ments principally on their igneous fusion, and afterwards refined by 
the application of acid and alkaline menstrua, by Margraaf, fiergman, 
Bayen, and Achard, received still greater improvements from i 




26 INTRODUCTION^ 

labours of Klaproth, Vauquelin, and Hatchett. Hoffman, in the be- 
ginning of the 1 8th century, pohUed out magnesia as a peculiar sub- 
stance*. Margraaf, about fifty years latert, distinguished accurately 
between the silicious, calcareous, and aluminous earths. Scheele, 
in 1774, discovered barytes. Klaproth^, in 1788, made known zir- 
cone. Dr, Hope||, strontites in 1791. Gadoiin, ittriaH in 1794; and 
Vauquelin, gliicine in 1798. 

Seven nietals only had been accurately known to the ancients, 
gold, silver, mercury, copper, lead, tin, and iix»n. Zinc, bismutli, 
arsenic, and antimony, though mentioned by the Greek and Roman 
Authors, yet were employed only in certain combinations, and the 
production of them in the form of reguli or pure metals, was owing 
to the alchemists. 

Cobalt had been used to tinge glass in Saxony in the sixteenth 
century ; but the metal was unknown till the time of Brandt, and 
this celebrated Swedish chemist discovered it in 1733. Nickel** was 
procured by Cronstedt in 1751. The properties of manganese, which 
was announced as a peculiar metal by Kaimft in 1770, wereminute- 
^y investigated by Scheele and Bergman a few years after. Molyb- 
die acid was discovered by Scheele in 1778) and a metal procured 
from it by Hielm in 1783, the same year that tellurium was made 
known by MuUcr. Scheele discovered tungstic acid in 1781; and 
soon after a metal was extracted from it by Messrs. D'Elhuyars. 
Klaproth discovered ui*anium in 1789||. The first description of the 
properties of the oxide of titanium was given by Gregor in 1791||||. 
Vauquelin made known chromium in 1 7971(11; Hatchett columbium 
in 1 80 1 *** ; and shortly after, the same .substance was nouced by £ke- 

• HofTman, Opera, Tom. iv. pag. 479. 

t Opuscules, Tom. ii.pag. 137. 

:} Annales de Chimie, Tom. i. pag. 183. 

II Edinburgh Trans. Vol. iv. p. 44. 

t Creirs Annals, 1796. 

•* Bergman, Opuscula, Tom. ii. page 22. 

tt i>^ Metallis dubiis, p 48. 

^\ Journal de Physique, 1789, pag. 39. 

nil Annales de Chimie, xii. pag. 147. %% Ibid. xxv. 21. 

•** Phil. Trans. 1802. 



( 



INtftODUCTlOK. 27 

berg, and named by him tantalium. Cerium was discovered in 1 804, 
by Kissinger and Berzelius. Platina had been brought into Europe 
and examined by Lewis in 1 749 : and in 1 803, Descotils, Fourcroy, 
and Vauqiiclin announced a new metallic substance in it ; but the 
complete investigation of the properties of this extraordinary body 
was reserved for Messrs. Tennant and Wollaston, who in 1803 and 
1 804 discovered in it no less than four new metallic substances, be« 
sides the body which exists in it in the largest proportion, namely^ 
iridium, osmium, palladium, and rhodium. 

The attempts made to analyse vegetable substances previous to 
1 720, merely produced their resolution into the supposed elements 
of the chemists of those days, namely, salts, earths, phlegm, and sul- 
phur. Boerhaave and Ncwmann attempted an examination by fluid 
menstrua, which was pursued witli some success by Rouelle, Mac- 
quer, and Lewis. Scheele, between 1770 and 1780, pointed out se- 
veral new vegetable acids. Fourcroy, Vauquelin, Deyeux, Seguin, 
Proust, Jacquin, and Hermbstadt, between 1780 and 1790, in various 
interesting series of experiments, distinguished between different se- 
condary elements of vegetable matter, particularly extract, tannin, 
gums, and resinous substances ; and investigations of this kind have 
l>een pursued witli great success by Hatchett, Pearson, Shraeder, 
Chenevix, Gehlen, Thomson, Thenaixl, Chevreul, Kind, Brande, 
Bostock, and Duncan. The chemistry of animal substances has re- 
ceived great elucidations from several of the same enquirers ; and 
Berzelius has examined most of their results, and has added several 
new ones, in a comprehensive work expressly devoted to the sub- 
ject, published in 1808. 

That solid masses fell from above, connected with the appearance 
of meteors, had been advanced as eai'Iy as 500 years before the 
Christian aera, by Anaxagoras ; and the same idea had been brought 
forward in a vague manner by other enquirers among the Greeks 
and Romans, and was revived in modem times; but till 1802 it was 
regarded by the greater number of philosophers as a mere vulgar 
error, when Mr. Howard, by an accurate examination of the testi- 
monies connected %vith events of this kind, and by a minute analysis 
of the substances said to have fallen in different parts of the globe, 
proved the authenticity of the circumstance, and shewed that these 



\ 



28 INTRODUCTION* 

meteoric productions differed from any substances belonging to our 
earth ; and since that period a number of these phenomena have 
occurred, and have been minutely recorded. 

The philosophy of heat, the foundations of which were laid be- 
twt:cn 1757 and 1785, by Black, Wilcke, Crawford, Irvine, and La- 
voisier, since that period has I'eceived some new and very important 
additions^ from the enquiries of Pict«:t, Rumford, Herschel, Leslie, 
Dalton, and Gay Lussac. The circumstances under which bodies 
absorb and communicate heat, have been minutely investigated ; and 
the important discoveries of the different physical and chemical pow- 
ers of the different solar rays, and of a property analogous to pola- 
rity in light, bear immediate relation to the most refined doctrines of 
corpuscular science, and promise to connect, by close analogies, the 
chemical and mechanical laws of matter. 

A general view of the philosophy of chemistry was published un- 
der the same of Chemical Statics, in 1 803, by the celebrated Ber- 
thollet. It is a work remarkable for the new vi6ws that it contains 
on tlic doctrines of attraction ; views which are still objects of dis- 
cussion, and which bear an immediate relation to some of the con- 
clusions depending upon very recent discoveries. 

At the time when the antiphlogistic theory was established, elec- 
tricity had little or no relation to chemistry. The grand results of 
Franklin, respecting the cause of lightning, had led many philoso- 
phers to conjecture, that certain chemical changes in the atmo- 
sphere, might be connected with electrical phsenomena ; — and elec- 
trical discharges had been employed by Cavendish, Priestley, and 
Vanmarum, for decomposing and igniting bodies ; but it was not till 
the era of the wonderful discovery of Volta, in 1800, of a new elec- 
trical apparatus, that any great progress was made in chemical in- 
vestigation by means of electrical combinations. 

Nothing tends so much to the advancement of knowledge as the 
application of a new instrument. The native intellectual powers of 
men in different times, are not so much the causes of the different 
success of their labours, as the peculiar nature of the means and ar- 
tificial resources in their possession. Independent of vessels of 
glass, there could have been no accurate manipulations in common 
"^"•^^stry : the air pump was neccssaiy for the mvestigation of the 



INTRODUCTION. 29 

properties of gaseous matter ; and without the Voltaic apparatus, 
there was no possibility of examining the relations of electrical po- 
larities to chemical attractions. 

By researches, the commencement of which is owing to Messrs. 
Nicholson and Carlisle, in 1800, which were continued by Cruick- 
shank, Henry, Wollaston, Children, Pepys, Pfaff, Desormes, Biot, 
Thenard, Kissinger, and Berzelius, it appeared that various com- 
pound bodies were capable of decomposition by electricity ; and ex- 
periments, which it was my good fortune to Ristitute, proved that se- 
veral substances which had never been separated into any other forms 
of matter in the common processes of experiment, were susceptible . 
of analysis by electrical powers : in consequence of these circum- 
stances, the fixed alkalies and several of the earths have been shewn 
to be metals combined with oxygene ; various new agents have been 
furnished to chemistry, and many novel results obtained by their ap- 
plication, which at the same time that they have strengthened some 
of the doctrines of the school of Lavoisier, have overturned others, 
and have proved that the generalizations of the antiphlogistic phi- 
losophers were far from having anticipated the whole progress of 
discovery. 

Certain bodies which attract each other chemically, and combine 
when their particles have freedom of motion, when brought into 
contact, still preserving their aggregation, exhibit what may be call- 
ed electrical polarities ; and by certain combinations these polarities 
may be highly exalted ; and in this case they become subservient to 
chemical decompositions ; and by means of electrical arrangements 
the constituent parts of bodies are separated in a uniform order, 
and in definite proportions. 

Bodies combine with a force, which in many cases is correspon- 
dent to their power of exhibiting electrical polarity by contact ; and 
heat, or heat and light, are produced in proportion to the energy of 
their combination. Vivid inflammation occurs in a number of cases 
in which gaseous matter is not fixed ; and this phaenomenon hap- 
pens in various instances without the interference of free or 
combined oxygene. 

Experiments made by Richter and Morveau had shewn that, 
when there is an interchange of elements between two neutrals salts, 



so INTRODUCTION. 

there is never an excess of acid or basis ; and the same law seemtt 
to apply generally to double decompositions. When one body 
combines with another in more than one proportion, the second pro- 
portion appears to be some multiple or divisor of the first ; and this 
circumstance, observed and ingeniously illustrated by Mr. DaltoHs 
led him to adopt the atomic hypothesis of chemical changes, which 
had been ably defended by Mr. Higgins in 1789, namely, that the 
chemical elements consist of certain indestructible particles which 
unite one and one, or dne and two, or in some definite numbers. 

Whether matter consists of indivisible corpuscles, or physical 
points endowed with attraction and repulsion, still the same conclu- 
sions may be formed concerning the powers by which they act, and 
the quantities in which they combine ; and the powers seem capable 
of being measured by their electrical relations, and the quantities 
on which they act of being expressed by numbers. 

In combination certain bodies form regular solids ; and all the va- 
rieties of crystalline aggregates have lieen resolved by the genius of 
Haiiy into a few primary forms. The laws of crystallization, of 
definite proportions, and of the electrical polarities of bodies, seem 
tp be intimately related; and the complete illustration of their con- 
nection, probably will constitute the mature age of chcmistr}'. 

To dwell more minutely upon the paiticular merits of the chemi- 
cal philosophers of the present age, will be a grateful labour for 
some future historian of chemistry ; but for a contemporary writer, 
it would be indelicate to assume the right of arbitrator, even where 
praise only can be bestowed. The just fame of those who have en- 
lightened the science by new and accurate experiments, cannot fail 
to be universally acknowledged; and concerning the publication of 
novel facts there can be but one judgment} for facts are independent 
of fashion, taste, and caprice, and are subject to no code of criticism ; 
they are more useful perhaps even when they contradict, that when 
they support received doctrines, for our theoiies are only imperfect 
approximations to the real knowledge of things ; and, in physical re- 
search, doubt is usually of excellent effect, for it is a principal mo- 
tive for new labours, and tends continually to the dcvelopemeiu 
©f truth. 



INTRODUCTION. 31 

The slight sketch that lias been given of the progress of chemistry i 
has necessarily been limited to the philosophical details of discovery. 
To point out in historical order the manner in which the truths of 
the science have been applied to the arts of life, or the benefits de- 
rived by society from them, would occupy many volumes. From 
the first discovery of the production of metals from rude ores, to 
the knowledge of the bleaching liquor, chemistry has been continual- 
ly subservient to cultivation and improvement. In the manufacture 
of porcelain and glass, in the arts of dyeing and tanning, it has added 
to the elegancies, refinement, and comforts of life ; in its application 
to medicine it has removed the most formidable of diseases ; and 
in leading to the discovery of gunpowder, it has changed the institu- 
tions of society, and rendered war more independent of brutal strengtli, 
less personal, and less barbarous. 

It is indeed a double source of interest in this science, that whilst 
it is connected with the grand operations of nature, it is likewise 
subservient to the common processes as well as the most refined 
arts of life. New laws cannot be discovered in it, without increasing 
our admiration of the beauty and order of the system of tlie universe ; 
and no new substances can be made known which are not sooner or 
later subservient to some purpose of utility. 

When the great progress made in chemistry within the few last 
years is considered, and the number of able labourers who are at 
present actively employed in cultivating the science, it is im- 
possible not to augur well concerning its rapid advancement and 
future applications. The most important truths belonging to it are 
capable of extremely simple numerical expressions, which may be 
acquired with facility by students ; and the apparatus for pursuing 
original researches is daily improved, the use of it rendered more 
easy, and the acquisition less expensive. 

Complexity almost always belongs to the early epochs of every 
science ; and the grandest results are usually obtained by the mo'n'- 
simple means. A great part of the phacnomena of chemistry nso- 
be already submitted to calculation ; and there is great reason to hr- 
lieve, that at no very distant period the whole science will be capabl* 
of elucidation by mathematical principles. The relations of tl„ 
common metals to the bases of the alkalies and earths, and tht; i.;i ., 



32 INTRODUCTION* 

dations of resemblance between the bases of the earths and acids, 
point out as probable a similarity in the constitution of all inflamma- 
ble bodies ; and there are not wanting experiments, which render 
their possible decomposition fiir from a chimerical idea. It is con- 
trary to the usual order of things, that events so harmonious as 
those of the system of the earth, should depend on such diversified 
agents, as are supposed to exist in our artificial arrangements ; and 
there is reason to anticipate a great reduction in the number of the 
undecompounded bodies, and to expect that the analogies of nature 
will be found conformable to the refined operations of art. The 
more the phaenomena of the universe are studied, the more distinct 
their connection appears, the more simple their causes, the more 
magnificent their design, and the more wonderful the wisdom and 
power of their Author. 



ELEMENTS 



OF 

CHEMICAL PHILOSOPHY. 

PART I. 

> 

ON THE LAWS OF CHEMICAL CHANGES: 

ON 

UNDECOMPOUNDED BODIES jM". 

AND 

THEIR PEIMART COMBINATIONS. 



& 



k 



ELEMENTS, &c. 



DIVISION I. 

ON THE POWERS AND PROPERTIES OF MATTER, AND THE 
GENERAL LAWS OF CHEMICAL CHANGES. 

I. Preliminary Obaervationw, 

1. 1 HE forms and Appearances of the beings and substances of the 
external world are almost infinitely yarlous, and they are in a state of 
continued alteration : the whole surface of the earth even undergoes 
modifications : acted on by moisture and air, it affords the food of 
plants ; an immense number of vegetable productions arise from ap- 
parently the same materials ; these become the substance of ani- 
mals ; one species of animal matter is converted into another ; the 
most perfect and beautiful of the forms of organised life ultimately 
decay, and are resolved into inorganic aggregates ; and the same ele- 
mentary substances, differently arrang^, are contained in the inert 
soil, or bloom ar,d emit fragrance in the flower, or become in ani- 
mals the active organs of mind and intelligence. In artificial opera- 
tions, changes of the same order occur : substances having the cha- 
racters cf earths are converted into metals; clays and sands are 
united so as to become porcelain ; earths and alkalies are combined 
into glass ; acrid and corrosive matters are formed from tasteless 
substances ;— -colours are fixed upon stuffs, or changed, or made to 
disappear ; and the productions of the mineral, vegetable, and animal 
kingdoms are converted into new forms, and made subservient to the 
purposes of civilized life. 



-iC 






ir .13^ lilt 11 ite 

3t iLfe«IL 




IL Zr-i 



trjmf^ 





X a Ilf «ilBIBL 



trnishl '^Qiinxi». biu v'iks. rissx Knift 
JL numr air iwsws .-c 




? 



C 37 ] 

great mechndcal force is required to make them occupy a space 
perceptibly smaller. 

4. Elastic fluids or gaasesj the third class, exist free in the atmo- 
Inhere ; but they may be confined by solids, or by solids and fluids^ 
and their properties examined. Their parts are hig^hly moveable; 
they are compressible and expansible, and their volumes are inverse* 
ly as the weights compressing them. All known elastic fluids ar* 
transparent, and present only two or three varieties of colour ; thejr 
differ materially in density. 

5. Besides these forms of matter which are easily submitted to 
experiment, and the parts of which may be considered as in a state 
of apparent rest, there are other forms of matter which are known to 
us only in their states of motion when acting upon our organs of 
sense, or upon other matter, and which are not susceptible d being 
confined. They have been sometimes called etherial substancesj 
which appears a more unexceptionable name than imfionderabte nib" 
stances. It cannot be doubted that there is matter in motion in space» 
between the sun and the stars and our globe, though it is a subject 
of discussi(Mi whether successions of particles be emitted from these 
heavenly bodies, or motions communicated by them to particles in 
their vicinity, and transmitted by successive impulses to other par* 
tides. Etherial matter differs either in its nature or in its affec- 
tions by motion ; for it produces different effects ; for instance^ as 
radiant heat, and as different kinds of light. 

6. The various forms of matter, and the changes of these forms, 
depend upon acUve powers, such as gravitation, cohesion, calorific 
repulsion or heat, chemical attraction, and electrical attractiony the 
laws of which it is necessary to study with attention. 

III. Gravitaticm, 

1. When a stone is thrown into the atmosphere, it rapidly des- 
cends towards the surface of the earth. This is owing to ^ravira- 
tioH. All the great bodies in the umverse are urged towards each 
other by a, similar force. A cannon ball sent from a piece of artil- 
lery describes a curve, and at last fells to the ground ; were the im- 
pulse given to it by the gunpowder increased.to a certain extent, ujid 



^ 



[ 40 ] 

18 ice become at the degree of heat at which water bmis 101|8SS» 
All the elastic fluids, or the different species of air that have beea 
examined, as has been demonstrated by Messrs. Dalton and Qkj 
IfUssac, expand alike when heated to the same degree ; 100 parts of 
each at the freezing point of water becoming about 137|5 at the 
boiling point 

It is evident that the density of bodies must be diminished by ex- 
pansion ; and in the case of fluids and gasses, the parts of which ar» 
mobile, many important phaenomena depend upon this circumstance. 
If heat be applied to fluids or to gasses, the heated parts change 
their places and rise ; and the colder parts descend and occupy their 
places. CuiTents are constantly produced in the ocean and in great 
bodies of water, in consequence of this effect. The heated water 
rises to the surface in the tropical climates, and flows towards colder 
ones : thus the warmth of the gulf stream is felt a thousand miles 
from its source ; and deep currents pass from the colder to the 
warmer parts of the sea : and the general tendency of these changes 
is to equalize the temperature of the globe. 

In the atmosphere heated air is c(mstantly rising, and colder air 
rushes in to supply its place ; and this event is the principal cause 
of winds : the air that flows from the poles towards the equator, in 
consequence of the rotation of the earth, has less motion than the 
atmosphere into which it passes, and occasions an easterly current; 
the air passing from the equator tovrards the poles having more mo* 
tion, occasions a westerly current ; and by these changes, the difils* 
rent parts of the atmosphere are mixed together: cold is subdued 
by heat, moist air from the sea is mixed vdth dry air from the 
land, and the great mass of elastic fluid surrounding the globe 
preserved in a state fitted for the purposes of vegetable and aTtim^ 
life. 

3. There are very few exceptions to the law of the exfutneion of 
bodies, at the time they became capable of communicating the 
sensation of heat; and these exceptions seem entirely to depend 
upon some chemical change in the constitution of bodies, or on their 
crystalline arrangements. Thus clay contracts considerably^ in 
dimensions by a very intense heat, and on the measure of its con- 
tractions the pyrometer of Wedgwood is founded : but in this case 



J 



> 



[ 41 3 

the clay first gives olf water, which was united to its parts, and 
afterwards these parts cohere together with more force, and from 
being in a state of loose aggregation become strongly united. 
Water expands a little before it congeals, and expands considerably 
during its conversion into ice ; but in this case it assumes the crys- 
talline form ; and its parts whilst they are arranging themselves to 
form regular solids, probably leave greater interstices than they oc* 
cupied when at uniform distances in the fluid. Thus the same 
weight of matter will occupy much more space when arranged in a 
certain number of octahedrons, than when arranged in a fllmilar 
number of cubes, or hexagonal prisms. Certain saline solutions 
likewise, that shoot into prismatic crystals, expand at the moment 
they become solid ; and the case is the same with cast-iron, bbmuth^ 
and antimony. 

The expansion of water during its conversion into ice, is shewn 
by the circumstance of ice swimming upon water ; and if water in 
a deep vessel be examined at the time ice is forming, it will be 
found a little warmer at the bottom than at the top ; and these circum- 
st£lnces are of great importance in the (economy of nature. Water 
congeals only at the surface, where it is liable to be acted upon by 
the sun, and by warm currents of air which tend to restore it to the 
fluid state ; and when water approaches near the point of freezing it 
begins to descend, so that no ice can form till the whole of the water 
has been cooled to the point where it possesses the great density ; 
and in the deep parts of the sea and lakes, even in some of the 
northern latitudes, the duration of the long ^vinter is insufficient to 
cool the water to the degree at which ice forms. 

4. When equal quantities of the same matter differently heated 
are mixed together, as much as the one contracts, so much the 
other seems to expand. It is easy to prove this by shaking together 
100 parts of mercury so hot as not to be touched without pain, and 
100 parts in its common state, having previously measured the space 
they occupy ; if the mixture is made in the tube that contained the 
hot mercury, there will be no sensible change of volume. 

It is oti the idea, that when heat or the power of repulsion is com- 
mumcated from body to body, as much is gained by one body as is 

» • 



s 



C 42 ] 

lost by the other, that thermometers have been framed, and drib 
doctrines of temperature, and capacity for heat foimded. 

5. The most common thermometer is a glass bulb, contmuun^ ' 
mercury, terminated by a glass tube, having a very narrow bore. The 
mercury is boiled to expel any air or moisture that might be attach- 
ed to it ; and at the moment it is in ebullition, the extremity <^ the 
tube being drawn to a fine point, is hermetically sealed by a spirit 
lamp. For the purpose of acquiring a scale, the bulb is first plunge 
cd into melting ice, and the place where the mercury stands is 
marked ; the bulb is afterwards plunged into boiling water, and the 
same operation repeated. On Fahrenheit's scale this space is divid- 
ed into 1 80 equal parts, and similar parts are taken above and belov 
for extending the scale, and the freezing point of water is placed at 
32**, and the boiling point at 212^ 1.8 degrees of Fahrenheit are 
equal to one degree of the centigrade thermometer, and 3.35 to one 
degree of Reaumur. 

Other fluids besides mercury, such as alcohol, are sometimes 
used in thermometers, particularly for measuring low degrees when 
mercury freezes. 

Air is employed in the differential thermometer, which consists of 
two bulbs filled mth air, and connected by a capillary tube contauo* 
ing oil of vitriol : the heated body is brought in contact with one 
bulb, the air of which expands and drives the fluid towards the 
other bulb*. 

6. Temfierature is the power bodies possess of communicating or 
receiving heat, or the energy of repulsion ; and the temperature of 
a body is said to be high or low with respect to another, in propor- 
tion as it occasions an expansion or contraction of its parts ; and the 
thermometer is the common measure of temperature. 

7. When equal volumes of different bodies of different tempera- 
tures are suffered to remain in contact till they are possessed of the 
same temperature, it is found that this temperature is not a mean 
one, as it would be in the case of equal volumes of the same^body. 

• Plate I. fig. 2, represents Mr. Leslie's differential thermometer. Fig. 3 is copied 
from Van Hclmont. This instrument appears to have been the first in which tht 
insive power of heated air, was exhibited by its action upon cold air. 



[ 43 ] 

Thus, if a pint of quicksilver at 100°, be mixed with a pint of water 
at 50% the resulting temperature is not 75°, but about 70°: the 
mercury has lost 30% whereas the water has gained only 20®. In 
the common language of chemical philosophers this difference is 
said to depend upon the different cafmcitiea of bodies for heat, and 
the cafiacity of a body is said to be greater or less, in proportion as 
its temperature is less or more raised by the addition, or diminished 
by the subtraction of equal quantities of the power of repulsion, or 
heat. Thus mercury is said to have a much less capacity for heat 
than water; and taking the facts above stated as data, and compar- 
ing the weights of the two bodies, which are as 13.3 to 1, their 
capacities will be to each other as about 19 to 1. 

Tables of the relative capacities of bodies are given in the works 
of different authors. In referring to the various bodies which are 
the subjects of chemistry, this property will be described amongst 
other properties. In general it appears that the substances most 
expansible by heat are those which have the greatest capacities: 
thus gasses in general have greater capacities than fluids, and fluids 
than solids ; but the exact ratio has not been yet determined. 

8. Different bodies, it appears, have their temperatures different- 
ly raised by the addition, or diminished by the subtraction of equal 
quantities of heat, or the power of repulsion, and they are likewise 
affected by heat, or expanded, with very different degrees of celerity. 
If slender cylinders of silver, of glass, and of charcoal, of equal 
length and size, be held in the central part of the flame of a candle, 
the silver rapidly becomes heated throughout, and cannot be held in 
the hand ; the heat is more slowly communicated through the glass> 
but the charcoal becomes red-hot at the one extremity long before- 
any heat is felt at the other extremity. These differences are said 
to depend upon the different powers of these bodies for conducting 
heat ; thus the silver is said to be a better conductor than the glass, 
and the glass than the charcoal. In general those bodies that are 
the densest, and that have the least capacity for heat, are the best 
conductors : thus the metals conduct better than any other solids j 
gasses are worse conductors than fluids, and fluids than solids: but 
there are exceptions with respect to this correspondence between 
conducting power and density, and a remarkable one, in the densest 



[ 44 ] 

known body in nature, platina, which is perhaps the worst conductor 
amongst the metals. 

Animal and vegetable substances in general, are very bad, con- 
ductors : thus the hair and wool of animals, and the feathers of 
birds, are admirably fitted to protect them from the cold, and they 
inclose and retain air, which being a still worse conductor, enhances 
the effect. It was supposed by Count Rumford, that fluids and 
gasses are perfect nonconductors of heat, and that their particles cas 
be heated in no other way, except by coming in succession to the 
source of heat ; but some very conclusive experiments seem ta 
render this opinion untenable. In general, however, fluids and 
gasses alter their places from a change of specific gravity, WMck 
more rapidly than they communicate or receive heat. This is illus- 
trated by a very simple experiment: let an air thermometer be nj- 
v^rted in a vessel of water, so that the extremity of the bulb is hardy 
beneath the surface, let a little ether be poured upon the water m 
as to form a stratum about one-eighth of an inch above the thermo< 
meter, and let the ether be inflamed*; however delicate the thermo- 
meter, the air in it will not soon expand ; the ether boils violently^ 
but a very long process of this kmd is required to communicate any" 
sensible heat to the water. Unless the particles of gasses and fluids 
had been capable of communicating heat to a certain extent^ the 
upper strata of liquids would be almost the only permanently heated 
parts ; and heat would be constantly accumulating on the sur&ce of 
extensive seas. Our lower atmosphere likewise would be intensely 
cold during the absence of the sun ; biit by the relations between 
the conducting power and the mobility of fluids and gasses, thfr 
changes of temperature of air and water are made progressive imd 
equable, and adapted to a habitable globe. As heat is propagated 
very slowly through gaseous bodies, so they communicate it very 
slowly to other bodies, a circumstance that might be expected from 
the small quantity of matter they contain, when compared to other 
substances. The heat of metals at the temperature of 120^ is 
scarcely supportable; water scalds at 150°; but air may be heated 
to 240° without being painful to our oi^ans of sensation, and a tem- 

• See Plate L fig. 4. 



C 45 ] 

perature near this was experienced for some minutes, by Sir Joseph 
Banks, Sir Charles Blagden, and Dr. Fordyce, in a room artificially 
heated. 

The power of abstracting heat in air is likewise comparatively 
very small; in the high northern latitudes a cold has been experi- 
enced without injury, in which mercury fVoze; and if, in this state 
of the atmosphere, metallic substances, of the same temperature, 
were touched, a sensation like that of burning was experienced, and 
the part blistered. 

9. Heat, or the power of repulsion, may be considered as the 
antagonist power to the attraction of cohesion, the one tending to 
separate, the other to unite the parts of bodies ; and the forms of 
bodies depend upon their respective agencies. In solids the attrac- 
tive force predominates over the repulsive ; in fiuids, and in elastic 
fluids, they may be regarded as in different states of equilibrium ; 
and in ethereal substances the repulsive must be considered as pre- 
dominating over, and destroying the attractive force. 

All the different substances in nature, under certain circumstances, 
are probably capable of assuming all these forms : thus solids, by a 
certain increase of temperature, becotne fiuids, and fluids gasses; and 
'vice versa^ by a diminution of temperature, gasses become fluids, and 
fluids solids. 

Instances of the fusion of solids by heat are too familiar to re- 
quire any particular notice ; when water becomes steam by boiling, 
it is merely the conversion of a fluid into an elastic fluid ; and a 
simple instance of this circumstance may be given in the ebullition 
of ether. Let a little ether be introduced into a small glass retort 
filled with water, and inverted in water : the ether will swim above 
the.water, in the upper part of the retort; let a heated bar of metal* 
be held near the part of the retort containing the ether, as the heat 
i^ communicated, globules will be seen to rise, and in a very short 
time ela9tic fluid wiH be formed, in such quantities, as to expel the 
water from the vessel: 6n suffering the glass to cool, the elastic 
matter will be condensed, and will become again fluid. 

If a globule of mercury be held in a spoon of platina, over the 
Hame of a lamp, it will be vividly agitated, and will rapidly diminish. 

♦ Plate I. fig. 5. 



C 46 i 

This is owing to its becoming elastic, and flying off in gas : and b^ 
a very low temperature, which may be artificially produced by mix- 
ing together very cold snow and a salt called muriate of lime, mer- 
cury may be congealed into the solid form. 

Different bodies change their states at very different temperatures. 
Thus mercury, which is a solid at about 40® below Fahrenheit, bcMla 
at about 660°; sulphur, which becomes fluid at 218% boils at 575**; 
ether boils at 98°. The temperatures at which the common metals 
become gaseous, are generally very high, and most of them incapa- 
ble of being produced by common means. Iron, maganese, platina, 
and some other metals, which can scarcely be fused in the best fur- 
naces, are readily melted by electricity ; and by the Voltaic appara- 
tus a degree of heat is attained, in which platina not only fuses with 
readiness, but seems even to evaporate. 

With respect to the conversion of solids, fluids, or gasses, into 
ethereal substances, the proofs are not of the same distinct nature as 
' those belonging to their conversion into each other. When thtt 
temperature of a body is raised to a certain extent, it becomes lumiB-' 
ous ; and heated bodies not only affect other bodies by direct contact^ 
but likewise exert an influence on them at a distance, which is as* 
cribed to what is usuaUy called radiant heat. One solution of tins 
phaenomenou is, that particles are thrown off from heated bodies 
with great velocity, which by acting on our organs produce the sen- 
sations of heat or light, and that their motion, communicated to the 
particles of other bodies, has the power of expanding them : thus if 
heat, or the force of repulsion, be so increased in an elastic fluid, as 
to overcome the force of cohesion and gravitation, these particles 
would move in right lines through free space ; and we know of no 
other effiects they could produce, than those of heat and light. It is 
perhaps in favour of this opinion, that all the different elastic fluids 
expand equally, when their temperatures are equally raised ; and 
from observations made on the eclipses of Jupiter's satellites, and 
from other phenomena presented by the heavenly bodies, it appears 
that the motions of light are equable. 

It may, however, be said, that the radiant matters emitted by 
bodies in ignition, are specific substances, and that common noatter 
is not susceptible of assuming this form; or it may be contended,- 



[ 47 ] 

that the phaenomena of radiation do, in fact, depend upon motions 
commanicated to subtile matter every where existing in space. 

9. I'he temperatures at which bodies change their states from fluids 
to solids, though in general definite, are influenced by a few circum- 
stances, such as motion and pressure. Water, kept perfectly at rest, 
may sometimes be cooled to 22°, without congelation ; but if at a tem- 
perature below 32° it be agitated, ice instantly forms. A saturated 
solution of Glauber's salt, introduced whilst warm into a bottle, from 
which the pressure of the atmosphere is excluded, renudns liquid 
after cooling, but if the atmosphere be suffered to act upon it, it in- 
stantly crystallizes. The boiling point of fluids is still less fixed, 
than the point of fusion of solids, and is immediately dependent upon 
pressure. Thus ether will boil readily at the freezing point of 
water, in the exhausted receiver of an air-pump ; and it appears 
from the researches of Professor Robison, that in a vacuum, all 
liquids boil about 145** lower, than in the open air. Under pressure, 
liquids may be heated to a high degree ; water in a Papin's digester, 
may have its temperature raised to 300^, but at the moment the 
pressure is removed, elastic matter is disengaged with great 
violence. 

10. A peculiar distinction has been made by some authors between 
permanent elastic fluids, and elastic fluids which are condensable 
by pressure or cold ; but these subtances differ only in the degree 
of the point of vaporization; and steam at 500 degrees of Fahrenheit, 
there is every reason to believe, would be equally incondensible with 
air at a range of temperature such as we can command below our 
common temperatures ; and some gasses that are permanent under 
all common circumstances, as ammonia, are condensible by intense 
cold aided by pressure. 

All bodies that boil at moderate temperatures, seem to evaporate, 
so' as to produce a certain quantity of elastic matter in the common 
state of the atmosphere ; and this quantity is greater in proportion 
as the temperature is high. According to Mr. Dalton, the force of 
va|>our increases in geometrical progression to the temperature, but 
the ratio differs in different fluids. It is certain that as the tempera- 
ture approiu^hes near the point of ebullition), in liquids, the strength 



[ 48 ] 

of the vapour^ i. e. the quantity that would rise in free space, rapitfy 
increases. 

In hot, dry weather, it is obvious that there must be much more 
vapour in the atmosphere, than in cold, wet weather; and the 
largest quantity exists in summer and in the tropical cUioates, 
when moisture is most needed for the purposes of life ; and it ap* . 
pears to be the aqueous vapour in the atmosphere, which, when 
condensed by the mixture of cold with hot air, or by other agencies 
occasioning a change of its temperature, is the cause of dew, mists, 
rain, and ultimately of springs, and rivers. 

11. When solids are converted into fluids, or fluids into gassed 
there is always a loss of heat of temperature, and vice versa, when 
losses are converted into fluids, or fluids into solids, there is an in- 
crease of heat of temperature, and in this case it is said that latetii 
heat is absorbed or given out. Thus if equal weights of snow at 
32° and of water at 172° be mixed together, the whole of the snow 
is melted, but the temperature of the mixture is found to be 33* 
so that 1 40° of heat are lost. Again, if M^ter be heated m "a 
Papin's digester to 300 degrees, and the valve be raised, a quantity 
of steam instantly rises, which has the temperature of 212^, and the 
tempierature of the water in the digester is found to be the same, 
so that a great quantity of heat of temperature is lost in converting 
the water into steam. 

If when the air is at 20°, a quantity of vrater be exposed to it in a 
tall glass, the water gradually cools down to 22°, without freezing; 
but if it be shaken, so as to be converted into ice, the temperatnreof 
the ice is found to be at 32°, so that the degree of heat is raised during 
the act of freezing. 

If one part of steam or aqueous gas, at 2 1 2°, be mixed with 6 
parts by weight of water, at 62®, the whole of the steam will be con- 
densed, and the temperature of the fluid will be about 213^, so UtaX 
there is an immense increase of the heat of temperature, and 900° 
may be considered as taken from the steam, and as added to the 
water. 

All the phaenomena of these changes may be referred to a simple 
general law, of which Dr. Black was the discoverer, and which has 
been most ably illustrated by the researches of Wilke, Watt, Ir- 



C 49 ] 

vkie, and Crawford, namely, " that whenever a body changes its 
form, its relations to temperature are likewise changed, cither in- 
creased or diminished ;" and many important operations, both ar- 
tificial and natural, depend upon this law. The knowledge of it) 
for instance, led Mr. Watt to make his great improvement of the 
steam engine, by which the steam is condensed out of the cylinder 
in which its force is efficient, and fresh gaseous matter introduced 
without any chance of a loss of its elasticity. • 

One of the most perfect modes of heating large rooms, and of pro- 
curing a uniform tempen^ture for the purposes of manufacture, b 
by the condensation of steam. By the cold produced in consequence 
of the evaporation of water in hot climates, congelation is effected ; 
and in the nights in Bengal, when the temperature is not below fifty, 
by the exposure of water in earthenware pans upon moistened bam- 
boos, thin cakes of ice are formed, which are heaped together and 
preserved under ground by being kept in contact with bad conduc- 
tors of heat. The cold produced by evaporation is likewise the 
cause of the formation of ice in Mr. Leslie's elegant experiment^ 
in which sulphuric acid is placed in a vessel upon the plate of an 
air-pump, and water in another vessel raised above it ; the surfaces 
both of the acid and the water being considerable. When an ex- 
haustion is made, the sulphuric acid rapidly absorbs the vapour rising 
from tlie water ; fresh vapour is immediately formed, and in a few 
minutes, if the circumstances are favourable, spiculae of ice arie seen 
to form on the surface of the water. 

When aqueous vapour is condensed into fiuid In the atmosphere^ 
heat is produced ; and the formation of rain, hail, and snow, tends to 
mitigate the severity of the winter. In the summer, evaporation is 
constantly tending to cool the surface. The melting of the polar 
ice moderates the heat that would arise in the northern regions from 
the constant presence of tlie sun during the polar summer. And the 
evolution of heat during the congelation of water, prevents too great 
a degree of cold, and renders the transitions of temperature more 
slow and gradual. 

12. When the forms of bodies are changed by mechanical means^ 
er when mechanical forces are made to act upon them, there is 
usually a change of temperature. A piece of caotchouc extended 



/ 



C so 3 

Q&d suffered to contract rapidly by mechanical means, becomes hot ; 
a nail is easily made red hot by a few well-directed blows of the ham* 
mer; and by the friction of solids, considerable increase of tempera- 
ture is produced : thus the axle-trees of carriages sometimes in- 
flame. 

By strong pressure, fluids even are made luminous, as has been 
lately shewn by M. Dcssaigncs. 

When an elastic fluid is compressed by mechanical means, its 
temperature is raised, and when the compressing forces are great 
and rapidly applied, the eflect is such as to cause the ignition of bodies. 
A machine for setting fire to tinder of the agaric, by the comLpres* 
sion of air, has been for some time in use. 

When air is made to expand by removing compressing forcesy a 
diminution of temperature is occasioned. Thus the mercury in the 
thermometer sinks at the time of the rarefaction of air, by exhaust 
ing the receiver of an air pump. 

In the common language of chemistry, it may be said that. the 
capacity of elastic fluids for heat is diminished by compression, and 
encreased by rarefaction ; and it is probable that when the volomet 
of elastic fluids are changed by change of temperature, there ia 
likewise a change of capacity ; and on these ideas it is easy to ac« 
count for the correspondence between the diminution of the tempera- 
ture of tlie atmosphere and its height ; for if it be conceived that the 
capacity of air rarefied by heat, increases as it ascends, the heat of 
temperature which was the cause of its ascent, must, at a certain 
elevation, become heat of capacity : and the higher and more rare- 
fied the air, the more it is removed from the source of heat, axMl the 
greater its power of diminishmg temperature. 

A veiy curious phaenomenon is produced during the action of the 
fountain of Hiero at Schemnitz in Hungary; the air in the machine 
is compressed by a column of water, 260 feet high, and when a 
stop-cock is opened so as to suffer air to escape, its sudden ran* 
faction produces a degree of cold which not only precipitates aqueous 
vapour, but causes it to congeal in a shower of snow, and the pipe 
from which the air issues becomes covered ^vith icicles. Dr. Dar- 
win has ingeniously explained the production of snow on the tops 
highest mountains by the precipitation of vapour from thm 




C 51 ] 

rarefied air which ascends from plains and valleys. The AndeSf 
placed almost under the line, rises in the midst of burmng sands ; 
about the middle height is a pleasant and mild climate; the summits 
are covered with unchanging snows : and these ranges of tempera* 
ture are always distinct; the hot winds from below, if they asccndf 
become cooled in consequence of expansion, and the cold air, if by 
any force of the blast it is driven downwards, is condensed, and 
rendered warmer as it descends. 

It seems probable that the capacity of solids and fluids is in* 
creased by expansion, and diminished by condensation, and if this 
is the case, the additions of equal quantities of heat will give 
smaller increments of temperature at high than at low degrees, 
which must to a certain extent render the thermometer inaccurate 
in the higher degrees, though probably only to a very small extent, 
of little importance as to all pracdcal purposes ; and this cause of 
inaccuracy appears to be counteracted by another, that fluids seem to 
be more expansible by heat in proportion as their temperature is 
higher. 

13. In all chemical changes there is an alteration of temperature ; 
and in most instances when gasses become fluids, or fluids solids, 
there is an increase of temperature ; and vice veraa^ there is usually 
a diminution of temperature when solids become fluids, or fluids 
solids. For instance, when the highly inflammable substance called 
phosphorus, the properties of which will be hereafter described, is 
burnt in the air, it is found to condense a particular part of the air, 
and a high temperature is produced during the process. When a 
a solid amalgam of bismuth, and a solid amalgam of lead, substances 
which ^11 be noticed in that part of this work relating to the me- 
tallic compounds, are mixed together, they become fluid, and the 
thermometer sinks during the time of their action. 

There are, however, a number of cases in which, though gaseous 
boifies or fluids are formed from solids, an increase of temperature 
occurs: thus, in the explosion of gunpowder a large quantity of aeri- 
form matter is disengaged, yet a violent heat is produced. 

And there is an instance in which at the time of the separation 
of two species of gaseous matter from each other, which is con* 
necled with expansion, there is aft increase of temperature ; thus, 



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^.v.*^'. ... .^.* ;- : r ;;■ ,. L vi:.:: a:i:r;*J:c fit" 2rx:*». 



[ 53 ] 

Since all matter may be made to fill a smaller volume by cooling, 
it is evident that the particles of matter must have space between 
them ; and since every body can communicate the power of ex- 
pansion to a body of a lower temperature, that is, can give an ex- 
pansive motion to its particles, it is a probable inference that its own 
particles are possessed of motion ; but as there is no change in the 
position of its parts as long as its temperature is uniform^ the mo- 
tion, if it exist, must be a vibratory or undulatoiy motion, or a mo- 
tion of the particles round their axes, or a motion of particles round 
each other. 

It seems possible to account for all the phxnomena of heat, if it 
be supposed that in solids the particles are in a constant state of 
vibratory motion, the particles of the hottest bodies moving with the 
greatest velocity, and through the greatest space ; that in fluids and 
elastic fluids, besides the vibratory motion, which must be conceived 
greatest in the last, the particles have a motion round their own axes, 
with different velocities, the particles of elastic fluids moving with 
the gi-eatest quickness ; and tliat in etherial substances the particles 
move round their own axes, and separate from earh other, penetraung 
in right lines through space. Temperature may be conceived to de- 
pend upon the velocities of the vibrations ; increase of capacity on 
the motion being performed in greater space; and the dimxnutioa 
of temperature during the conversion of solids into fluids or gasses 
may be explained on the idea of the loss of vibratory madon, in 
consequence of the revolution of particles round their axes, a: the 
moment when the body becomes fluid or xiiform. or from the kos 
dF rapidity of vibration, in consequence of the modoD of the pardcles 
thi'ough greater space. 

If a specific fluid of heat be admitted, it most be riy^ovid !ia.\'^ 
x> most of the affections which the particles of comscf^i TSjLr.er ir- 
tssumed to possess, to account for the phaenomcna; sQih ^a k^r^fi- 
ts motion when combining with bodies, prodccsaif iSLrrLrr. 
ransmitted from one body to another, and gaimagpr'/r'.r: It r:i 
vhen passing into free space: so that mux kypcrJi-^t^* -i; 
.dopted to account for its mode of i^;eiicT, vticl r^-.-iz-r z::s 
f the subject less simple than tbeotbcr. V*7t i;_iS*ri ^ 
aents have been made which shew tfat bafitt -r^'jir zexs*^-^ 



C 54 3 

biGTcase in wei^t. This, aa €ir as it goes, is an evidence against a 
^cific subtile elastic fluid producing the calorific expansion ; but it 
cannot be considered as decisiTe, on account of the imperfectioii of 
our instruments ; a cubical inch of inflammable air requires a good 
balance to ascertadn that it has any sensible weight, and a substance 
bearing the same relation to this, that this bears to platinum, could 
not perhaps be weighed by any methods in our possession. 

Some arguments have been raised in £iyour of the existence of a 
specific fluid ot heat, from the circumstances of the communicatico 
of heat to bodies in exhausted receivers, and from the manner in 
which they are affected by this heat ; but there are no means known 
in experimental science of producing a perfect vacuum ; even the 
best Torricellian vacuum must contain elastic matter. The great 
capacity of such highly rarefied matter, is an obstacle to the indica* 
tion of temperature ; but supposing a communication of heat« the 
laws must be analogous to those of heat communicated to comnNB 
air. If a long cylinder of metals placed perpendicularly, be beatfid 
in the middle, the warmest part will be above« from the ascent off 
heated particles of the elastic medium ; but if a ifihere be heated ■ 
the middle, the hottest poruon will be below, as the heated efastk 
matter must remain longer in contact with the inferior than with ths 
sa[>erior portion. 

The laws of the communication of heat, and the philosophy of ha 
effects, are independent of this speculative question, which will agua 
be considered, under new relations, in the part of this work relatiBp 
to the properties of etkcrial or radiant matter, 

VI. On chemical Attraction^ and the law9 cf Combination 

and Decumftontion. 

I . When olive oil and water are agitated together, they rcfiiae ti 
act upon each other, and separate according to the order f£ tbcir 
tensities, the oil swimming above the water. Oil and water wiB 
not mix inumately ; they wiil not combine ; and they are sud to 
have no chemical a.:trac:hn or affhzz:y for each other. Bctt if id 
and soap lees, or %la:ica of potassa in water« be mixed, the oil and 
"-he solution blend together, and a species of soap will be fbrmcd^ 



[ 55 ] 

which may he procured as a soft solid substance by evaporating a 
part of the water. This is an instance of combination i and solution 
of potassa and oil are said to attract each other chemically) or to 
have an affinity for each other. 

2. Oil is almost insipid, but the solution of potassa is a caustic 
substance, which corrodes the skin, and has a strong taste.— The 
body resulting from their union differs both from the oil and the al- 
kali in taste, smell, colour, and in all its sensible qualities ; and it is 
a general character of chemical combination^ that it changes the sen- 
sible qualities of bodies. 

Corrosive and pungent substances often become mild and tasteless 
by their union, as is the case with sulphuric acid and quicklimci 
which form gypsum, or sulphate of lime. 

Bodies possessed of little taste or smell often gain these qualities in 
a high degree by combination. Thus sulphur, when inflamed in oxy- 
gene or in common air, dissolves and forms an elastic fluid of a most 
penetrating and disagreeable odour and peculiar flavour. The forms 
of bodies, or their densities, likewise usually alter; solids become 
fluids, and solids and fluids gasses, and g^sses are often converted 
into fluids or solids. Thus sugar, or salt, or isinglass, dissolves in 
water. The consumption of charcoal in our flres depends upon its 
uniting with a part of the air, with which it forms an invisible elastic 
fluid : mercury is rendered solid by being heated with half its weight 
%>f tin, and a substance of this kind is used for silvering mirrors. The 
gas produced by the combustion of charcoal is condensed by another 
^as procured from quicklime and sal ammoniac, when they are mix- 
ed over mercury ; and the two invisible elastic fluids form a white 
saline solid. 

3. Many substances may be made to unite by chemical affinity or 
attraction : thus common salt, sugar, and pearl-ashes, will all dissolve 
together in water. And the fossil alkali, sand, and the glass of lead, 
when melted together, unite to form flint glass. And, in like man- 
ner, porcelain is formed by heating together mixtures of different 
earths. In a number of the productions of nature likewise many 
fi>ubstances are combined into one mass or compound. Thus many 
stones and gems are capable of being resolved into several elements ; 
and in the vegetable and animal kingdom there arc scarcely any 90m- 



C 56 ] 

pounds which do not contain more than two principles, md complesi" 
ty of constitution seems uniformly connected with organization. 

4. That chemical attraction may be exerted between bodieS) it is 
necessary that they should be brought into apparent contact. Thus 
no body will act chemically upon another at any sensible distance. 

5. A freedom of motion in the parts of bodies, or a want of c<die* 
uon, greatly assists combination ; and this circumstance b so mark- 
ed, that it was formerly considered as a chemical axiom, which is still 
retained in some elementary books, that bodies cannot act chemicalif 
on each other unless one of them be fluid or xnform. Such an ex- 
tensive generalization is, however, incorrect; thus ciystalline muriate 
of lime and snow, both cooled to O^' Fahrenheit, act upon each other 
and liquify; and crystals of oxalic acid and dry lime treated in the 
same manner readily combine. The hardest and the densest bodBes, 
however, undergo chemical changes with the greatest difficulQf. 
Thus the sapphire, in its crystallized state, is not affected by bcnlmg 
sulphuric acid ; but when in a fine powder, as alumine, it is easlf 
dissolved. Minute division, or solution, or fusion, is necessary in al- 
most all chemical processes. In the chemical arts these circum- 
stances are always attended to ; and in the phaenomena of extenal 
nature, the commencement of chemical operations may in almost tU 
cases be traced to -the agencies of fluids or* aeriform substances. 
Thus in the bosom of our rocks and mountains, where air and watier 
are incapable of penetrating, all is permanent and still, without chaag^ 
or motion ; wherever water and air are capable of acting, decompo- 
sition slowly goes on ; and these agents gradually change the natint 
of the surface, render the soil fertile, and decompose and degrade tbe 
exterior of strata. 

6. If equal weights of magneda and of quicklime, in fine powder, 
and diluted aquafortis or nitric acid, be mixed together, and suffered 
to remain for some hours, it will be found, by a minute examinatloDi 
that a considerable part of the lime has been dissolved, but all the 
magnesia will remain untouched. Hence, it is said, that lime has t 
stronger attraction for nitiic acid, than magnesia has. 

This is proved, likewise, by another experiment of a different 
kind : it is easy to make a solusion of magnesia, in nitric acid^ by 
heating them together ; and to make a solution of lime in water^ by 



C 57 ] 

agitating some powdered quicklime in distilled water. Let the so- 
lution of lime be poured into the solution of magnesia, a white pow- 
der or precipitate will separate, and gradually fall to the bottom of 
the vessel in which the mixture is made. This powder, when ex- 
amined, is found to be magnesia, and it is said that magnesia is pre- 
cipitated from nitric acid, in consequence of the stronger attraction 
of lime for that acid. 

All bodies, that diflTer in their nature, combine with different de- 
crees of force ; and some very important chemical phenomena in the 
arts depend upon this circumstance. Thus the astringent or tanning 
substance, in the bark of trees, wliich is soluble in water, is attracted 
from water, by the prepared skins of animals, in consequence of their 
stronger affinity for it, and the skin, from being destructible by boil- 
ing water, and decomposable, becomes indestructible and permanent. 
In like manner, indigo, and other dyeing materials, are separated 
from their^^^tions, by vegetable or animal fibres, and new combi- 
nations d^^HBbffected ; and a number of instances of the same kind 
might bflHjJPht forward. 

7, Different bodies unite with different degrees of force; and 
hence, one body is capable of separating others, from certain of their 
combinations ; and in consequence of the same circumstance, mutual 
decompositions of different compounds take place. This has been 
called double affinityy or complex chemical attraction. Thus, if an 
aqueous neutral solution of time and nitric acid, and a like solution 
of magnesia and sulphuric acid, be mixed together, the lime will 
quit the nitric acid, to unite to the sulphuric acid, and the magnesia 
•will leave the sulphuric acid, to combine with tlic nitric acid. The 
combination of nitric acid and magnesia, will remain in solution ; but 
the compound of lime and sulphuric acid, being only slightly soluble 
in water, will fbr the most part be precipitated, in the form of a 

white powder. 

In many cases decompositions, that cannot be produced by single 
attractions, may be produced by double affinities. Thus the elements 
of sulphate of baryta, gr the combination of sulphuric acid and the 
earth called baryta, arc so firmly united, that no alkali, nor earth, will 
separate the acid from the baryta. Potassa, which has a very strong 
attraction for tlie acid, will not decompose it alone ; but if potassa^ 

H 




[ 58 J 

combined witli carbonic acid, be digested for some time, witli pow* 
dered sulphate of baryta, there is a double decomposition ; and com' 
binations of sulphuric acid and potassa, and carbonic acid and barytai 
are formed. 

8. If one part of pure oxygene gas, and two parts of pure hydro- 
gene gas, in volume, be mixed together, in a glass tube, over mer- 
cury, furnished with wires for passing the electrical spark through 
it, and they be inflamed by the electrical spark*; the gaseous matter 
mil disappear, and water will result. If two parts of oxygene be 
employed, and two of hydrogene, one part of oxygene will remlun ; 
in whatever proportions they are mixed together, it is found, that 
one of oxygene always condenses two of hydrogene. It is evident, 
then, that oxygene and hydrogene combine only in definite propor- 
tions, and that the water resulting is always the same in its consd- 
tution. 

If a piece of well-burnt charcoal be introduced in|||ft|teHeI, two- 
thirds filled with oxygene gas, over mercury ; and^^^^hcury be 
brought to the same level on the inside and on the oua^PJBr the jv, 
and the charcoal be inflamed by a buming-glassf ; there 'will be it 
first an expansion, but after the experiment is over, it will be found, 
that the volume of the gas has not perceptibly altered ; and if the 
charcoal has been in sufficient quantity, the whole of the oxygene 
"will be found converted into carbonic acid ; now the densities of 
oxygene gas and carbonic acid gas, in whatever way they arc formed, 
arc always the same, and to each other as 34 to 47 nearly. It is 
evident, then, that carbonic acid must always contain the same weight 
of oxygene and charcoal. If there is twice as much oxygene in the 
vessel as is necessary for the consumption of the charcoal, half of it 
remains untouched ; and if the charcoal is partly unconsumed, still 
the gas is the same in quality ; it always contains by weight 5.7 of 
charcoal and 15 of oxygene. 

- There is an inflammable gas, called carbonic oxide, which bums 
M ith a blue flame, and which is obtained by igniting together zinc fil- 
higs and chalk. When two in volume of this j^as, and one in volume of 
oxygene, arc acted upon by an electric spark, over mercjury, they 

• See Plate I, fig. d. 
t Plate II, fig. 7. 



I 59 ] 

ififlame) and there result exactly two volumes of carbonic acid gas ; 
there is no other product, and the weight of the carbonic acid gas 
exactly equals the weight of the carbonic oxide and the oxygene 
gas ; so it is evident, that the carbonic oxide contains exactly half as 
much oxygene as carbonic acid, that is, 5.7 of charcoal require 7.5 
of oxygene to become carbonic oxide. Agaip this is proved by de- 
composition : if electrical sparks be passed through carbonic acid 
g^s, over mercury, it expands, and part of it is decomposed, two vo* 
lumes becoming two volumes of carbonic oxide, and one volume of 
oxygene. 

When tiie salt, called nitrate of ammonia, is decomposed by heat) 
an elastic fluid is disengaged, called nitrous oxide ; when one vo- 
lume of this g^ is mixed with one volume of hydrogene, and an 
electric spark is passed through the mixture, inflammation takes 
place, water is formed, and one volume of elastic matter remains, 
which is azote. Now, as one volume of hydrogene takes half a vo- 
lume of oxygene, for its conversion into water, it is evident, that this 
gas, nitrous oxide, must be composed of two in volume of azote, and 
one in volume of oxyg^e, condensed into a space equal to two. 

There is a gas produced by the solution of copper in diluted ni- 
tric acid. If a little of this gas be passed into a curved glass tube* 
over mercury, and metallic arsenic be sublimed in the g^s, it is gra- 
dually decomposed. A solid combination of arsenic and oxygene is 
formed, which is found (if the weight of the azote remaining be 
compared with that of the nitrous gas) to contain half a volume of 
oxygene, and half a volume of gas remains, which is azote. So it is 
evident, that as azote combined with one proportion of oxygene gas, 
. forms nitrous oxide, so combined with two proportions, it forms ni- 
trous gas ; and one volume of nitrous gas mixed over water with 
half a volume of oxygene, is condensed, and forms a solution of ni- 
trous acid gas in water. So that this body must consist of azote 
with four proportions of oxygene, nitrous oxide being considered as 
azote with one proportion of oxygene ; and the quantities in these 
bodies are always the same. 

It would be easy to bring forward a great collection of evidences 
to shew, that in all compound gaseous bodies, the quantities of the 

• Plate II, fig. 8 



[ 60 ] 

elements are uniform for each species*, and that when two gaseous 
elements combine in more than one proportion, that the second or 
third proportion is always a multiple, or a divisor of the first ; and 
the case seems to be analogous with respect to all true chemical 
compounds, whether solids or fluids, in which no mechanical mix- 
tures can be suspected, and where no partial decompositions can 
have taken place. 

Thus, if sulphuric acid be poured into any solution of baryta, the 
solid precipitate of sulphate of bar)'ta which falls down is uniform 
in its nature, and always contains about 34 of acid, and 66 of baryta; 
and the case is the same with other similar compounds, and with 
neutral salts in general. 

And if two neutral salts mutually decompose each other, in the 
interchange of principles, there is never an excess of acid or sf 

* That the proportions in compound gasses are definite has long been genenllf 
acknowledged; but Mr. Higgins is, I believe, the first person who conceived tint 
when gasses combined in more than one proportion, all the proportions of die 
same element were equal ; and he founded this idea, which was made public is 
1789, on the corpuscular hypothesis, that bodies combine particle with partide^ or 
one with two, or three, or a greater number of particles. Mr. Dalton, about 180% 
adopting a sinular hypothesis, apparently without the knowledge of what Mr. 
liiggins had written, extended his views to compounds in general. Mr. Bichter 
seems to have been the first person to shew that in the decompodtion of nential 
salts by double affinity, the neutral state is preserved ; and likewise that, when a 
metallic salt is decomposed by a metal, all the oxygene and acid is transfierred, nd 
the metal only changed, and that the new solution is as neutral as the former one. 
It had been ascertained, by different experiments, that in certain cases wheniofids 
dissolved in gasses, the volume is unchanged, and some instances of the combina- 
tion of gasses were known, in which the volumes bore simple ratios to each other» 
as in nitrous oxide, and water ; but M. Gay Lussac is the first philosopher who 
attempted to generalize on the phsenomena, and shew that, in all cases wheit 
gasses unite, it is always in simple ratios of volume, 1 to 1, or 1 to % or 1 to S| 
and that the condensation, if any, is in a simple ratio. His very ingemous idets 
on this subject were made known towards the close of 1808. Berzelius, in a work 
published in 1810, has determined very correctly some of the definite proportions 
of several important compounds. See JIiggins*s Coniparati'oe Viev). DaltonU Nev 
Chemical Philosophy. Richter Ueber die neuren gegenstande der Chetnie, Memoim 
iPArcueilj T. ii. Berzelius Annales de Chemie, T. Ixvii. Thomton^i Syttem ofChC' 
mistry, vol. iii. 



\ 



C 61 ] 

basis*, and the resulting compounds are likewise perfectly neutral. 
Thus, if 100 parts of niti*ate of baryta, which contain 41 nitric acid, 
and 59 baryta, be mixed with 67 of sulphat of potassa, which consist 
of 30 of sulphuric acid, and S7 potassa, there will be found 89 of 
sulphate of baryta, and 78 of nitrate of potassa ; so that 4 1 of nitric 
acid will combine with the 37 of potassa, and 30 of sulphuric acid 
witli the 59 of baryta. 

It is evident from these circumstances, that when one body has 
the power of detaching another from its combinations, it will always 
detach the same proportion. Thus, from whatever basis baryta at- 
tracts sulphuric acid, it will always detach the same quantity ; and 
the same quantity of potassa, from whatever acid it precipitates mag- 
nesia, will always throw down the same proportion. 

9. In cases when an alkaline substance combines with more than 
one proportion of acid, the same circumstances seem to occur as in 
the combinations of gaseous bodies. The proportion is cither a mul- 
tiple or a divisor of the first ; this is shewn by a very simple experi- 
ment, first made by Dr. WoUaston: let a given weight of the salt 
called carbonate of potassa be thrown into a tube over mercury, and 
diluted sulphuric acid sufficient to cover it be introduced into the 
tube, a certain volume of carbonic acid gas will be disengaged ; let 
an equal weight of the salt be heated to redness, when it becomes a 
subcarbonate, and let this subcarbonate be treated in the same way, 
it will be found to give off exactly half as much carbonic acid gas. 

10. In the combination of solid and fluid substances which have not 
•yet been decompounded, with gasses, and in the union of compound 

inflammable bodies with each other, and in all mutual decomposi- 
tions between bodies of this class, similar circumstances appear to 
occur : thus there are two combinations of mercury with oxygcnc, 
the black and the red ; and one appears to contain twice as much 
oxygene as the other. There are two known combinations of iron 
with oxygene, the black and the red oxide of iron ; and the oxygene 
in the first being considered as 2, that in the second must be consi- 

* M. M. Gay I^ossac and Thenard have lately stated, ** that, in some mutual 
decompositions of fiuates and muriates, slighdy acid solutions become alkaline/' 
Recherche; T. il page 28; but suoh changes mustlbe complicated ; and perhaps a 
minute Investigation may dhew that they are not anomalous. 









_: ""i* 



, ■ I I ^ M I* 



Tsse a 



rt TtimcBr s 



X -"•".»*■-• 






!0 






' «: - • 



.ru. 






f 63 ] 

exist in no definite compound in less proportion than water. Th0 
specific gravity of hydrogene is to that of oxTgene as 1 to 15; and 
as 2 Tolumes o£ hydrogene to 1 of oxjgene enter into the composi- 
tion of water, the ratio of the hydrogene in water will be to the 
oxygene as 2 to 15; and it may be regarded as composed of two 
proportions of hydrogene and one of oxygene: and the number re- 
presenting hydrogene will be 1, and that representing oxygene 15. 

The weights ci equal Tolumes of azote and oxygene are to each 
J other nearly as 13 to 15; therefore sopposing the number represent- 
ing the proportion^ in which azote combines, gained from the com- 
Xx>sition of nitrous oxide, which contains two volumes of azote to 
one of oxygene, it will be represented by 26 ; and nitrous oxide will 
consist of two proportions of azote equal to 26, and one proportion 
of oxygene, equal to 1 5. Xitrous gas will consist of 1 of azote and 
2 of oxygene, 26 and 30. Nitrous acid gas of 1 of azote and 4 of 
oxygene, 26 and 60. 

Ammonia, which is decomposed by electricity into 3 volumes of 
hydrogene and 1 volume of azote, will consist of 6 proportions of 
hydrogene and 1 proporticm of aaote, or 6 and 26. 

The weight of chlorine or oxymuriatic gas, is to that of hydros 
gene nearly as 33.5 to 1 ; and muriatic acid gas consists of equal 
volumes of these gasses, and therefore is composed of 33.5 of 
chlorine, and 1 of hydrogene ; — but 2 of chlorine may be .made to 
combine with one of oxygene in volume ; and double proportions of 
this gas combine to form compounds, which when decomposed by 
-water, afford compounds containing single proportions of oxygen, so 
that the ratio of chlorine to oxygene, is that of 67 to 15, and the 
number representing chlorine is correctly stated 67. 

In like manner it is easy to deduce the number representing the 
other undecompounded bodies; and they will be found to correspond as 
nearly as can be expected, in whatever way thev are obtained. Thus, 
-whether the number representing the proportion in which potassium 
the basis of potassa combuies, be gained from its combination with 
oxygene or with chlorine, the result wDl scarcely differ; for 8 grains 
of potassium converted into the compound of chlorine and potas- 
sium I have found gain about 7. 1 grains, and when converted into 
potassa, they gain a grain and j*^ ; and as 7.1 : 8 :: 67 : 75.4; and as 



/ 



[ 64 J 

1.6 : 8 :: 15 : 75, giving the number representing potassium as 
about 75, 

It is easy to form a series of proportional numbers by taking j of 
these numbers, on the supposition that water is composed of one 
proportion of hydrogene and one of oxygene ; but in this case the 
number representing the proportion in which oxygene combines 
must contain a fraction ; and the calculations are much expedited, 
and the formula rendered more simple, by considering the smallest 
proportion an integer. 

Mr. Higgins has supposed that water is composed of one particle 
of oxygene and one of hydrogene, and Mr. Dalton, of an atom of 
each ; but in the doctrine of proportions derived from facts, it is not 
necessary to consider the combining bodies, either as composed of 
indivisible particles, or even as always united, one and one, or one 
and two, or one and three proportions. Cases will hereafter be 
pointed' out, in which the ratios are very different; and at present, u 
we have no means whatever of judging either of the relative num- 
bers, figures, or weights, of those particles of bodies which arc not 
in contact, our numerical expressions ought to relate only to the 
results of experiments. 

If it should hereafter be discovered, that any of those substances 
now considered as undecompounded, ccuisist of other elements, 
these elements must be represented by some division of their 
numbers; and should even hydrogene be found a compounded body, 
it would merely be necessary to multiply all the numbers represent- 
ing the other elements, by some common number which woM 
admit of a division into proportions, representing the elements of 
hydrogene ; so that no discovery concerning the compositioa of 
bodies, can interfere with the general law of the definite natun of 
their combinations. 

12. If the black oxide of manganese be exposed to a strong heaty 
it gives off oxygene gas, and becomes brovni; but no heat as yet 
applied is capable of depriving it of the whole of its oxygene. 
Hence it is evident that when one proportion of one substance is 
combined with more than one proportion of another, the first pro- 
^rtions may be separated with much more facility than the last 

ere are numbers of other instances: thus the carbonate of soda; 



N 



[ 05 3 

which contains two proportions of carbonic acid to one of soda, giveB 
off half its carbonic acid with great facility, by heat, but obstinately 
retains the other half. Nitric acid is easily brought to the state of 
nitrous gas by the abstraction of oxygene : nitrous gas with more 
difficulty is converted into nitrous oxide, but nitrous oxide is still 
less decomposable than nitrous gas. 

When one proportion of a body is combined with two or more 
proportions of anotlier, it seems to enter with more difficulty into 
new combinations, than when it is combined wiUi one proportion* 
Thus iron combined with two proportions of sulphur in golden 
pyrites is not acted upon by diluted sulphuric acid: but when coiti« 
bined only with one proportion of suiphuri as in the common artifi' 
cial sulphuret, it is rcadiiy acted upon. 

It seems from these facts, that two or more proportions of one 
body attract a single proportion of another body witli moi*e energy 
than one proportion, and that two proportions or more adhere to a 
single proportion with less energy than one proportion; or at least 
that a second or a third proportion adheres with less energy tlian 
the first. 

It may possibly be said, that the effect of two or three proportions^ 
in defending one proportion from the action of a new substance, may 
depend upon mechanical causes, from their more completely en- 
veloping its parts ; but the other solution of the effect seems to be 
the most probable* 

13. M. Berthollet, to whom the first distinct views of the relations 
of the force of attraction to quantity arc owing, has endeavoured to 
prove that these relations are universal, and that elective affinities 
cannot strictly be said to exist. He considers the powers of bodies 
to combme as depending in all cases upon their relative attractions^ 
and upon their acting masses, whatever these may be : and he con* 
eeives that in all cases of decomposition, in which two bodies act 
upon a third, that third is divided between them in propoition to 
their relative affinities, and their quantities of matter* Were this 
proposition strictly correct, it is evident that tiiere could be scarcely 
any definite proportions : a salt crystallizing in a strong alkaline 
solution, would be strongly alkaline ; in a weak one less alkaline ; 
and in an acid solution, it would be acid ; which does not seem to 

t 




C 66 ] 

be the case. In combinations) in which gaseous bodies are concern* 
ed) the particles of which have perfect freedom of motion, the pro- 
portions are unchangeable ; and in all solid compounds, which have 
been accurately examined, and in which there is no chance of 
mechanical mixture, the same law seems to hold good. It is cer« 
tainly possible to dissolve different bodies in fluid menstrua, in vety 
various proportions, but the result may be a mixture of different 
solutions, rather than a combination. M. Berthollet brings £ar» 
ward glasses and alloys of metals, as compounds, containing in- 
definite proportions ; but it is not easy to prove, that in these, all 
the elements are chemically combined; and the points of fusion 
of alkali, glass, and certain metallic oxides, are so near each 
other, that transparent mixtures of them may be formed.— It cannot 
but be supposed, that the attractive power of matter is general, bat 
in the formation of aggregates, certain arrang^ements seem to be 
always uniform. 

14. M. Berthollet conceives, that he has proved tliat a large 
quantity of a body having a weak affinity, may separate a part of t 
second body, from a small quantity of a third, for which it has • 
strong affinity ; but even granting this, it does not destroy the idea 
of definite proportions. Thus in the fact, noticed by Bergman, the 
decomposition of sulphate of potassa by nitric acid, one proportion of . 
potassa may be separated from the acid; and the other proportion 
may combine with two proportions of acid ; phaenomena analogous 
to those of common double affinity. 

M. Berthollet states, that a large quantity of potassa will separate 
a small quantity of sulphuric acid from sulphate of baryta ; but he 
made his experiments in contact with the atmosphere, in which 
carbonic acid constantly floats; and carbonate of potassa and sulphate 
of baryta mutually decomposed each other (7). Even allowing title 
correctness of his views, still he has not given a complete statemoit 
of facts. If potassa separates sulphuric acid from baryta, either 
there must exist an insoluble sulphate of baryta, containing more 
baryta than tlie common sulphate, and which of course may contain 
two proportions of baryta; or baryta, sulphuric acid, and potassa, 
must all be dissolved, in the same fluid, which seems liighly impn>- 
bable. M. Berthollet regards baryta as separable from sulphuric 




C 67 ] 

acid) by potassa; but has not endeavoured to fthew in what form it 
appears after the process. 

1 5. M. Berthollet states, that soda is capable of separating a cer- 
tain quantity of potassa from sulphuric acid ; but, in his experiment, 
water was present, as the soda must have been a hydrate ; and he 
likewise used alcohol : and the phenomenon may be a phsno« 
menon of double attraction. Potassa has a much stronger attraction 
for water than soda; and the soda may quit its water, and the potassa 
its sulphuric acid; and the effect may be assisted by the stronger at- 
traction of hydrate of potassa for alcohol. 

In general, when large quantities of fluid or fusible bodies aie 
used in experiments, the attraction of the substances which are 
capable of acdng upon each other, is more rapidly brought into 
play. In many solutions all the elements arc in chemical combina* 
tion; and their separations depend not merely upon the relative 
attractions of their parts, but likewise on the manner in which they 
are acted on by water ; and earths, and oxides, are usually thrown 
down from their solutions in union with water. 

1 6; When an alkali precipitates an earth from its solution in an 
acid, the earth, according to M. Berthollet's ideas, ought to fall 
down in combination with a portion of acid, fiut if a solution of 
potassa be poured into a sulphuric solution of magnesia, the pre- 
cipitate produced, after being well washed, affords no indication of 
the presence of acid ; and M. Pfaff has shewn by some very decisive 
experiments, that magnesia has no action upon neutral combinations 
of the alkalies and sulphuric acid ; and likewise, that the tartarous 
acid is entirely separated from lime, and the oxalic acid from oxide 
of lead, by quantities of sulphuric acid, merely sufficient to saturate 
the two bases; and these are distinct and simple instances of elective 
attraction. Again, when one metal precipitates another from an 
acid solution, the body that falls down is usually free both from acid 
and oxygene: thus zinc precipitates lead and tin, and iron, copper; 
and the whole of the oxygene and the acid, is transferred from one 
metal to the other. 

17. M. Berthollet, in crystallizing sulphate of poUssa, from acid 
solutions, states that he obtained salts, of which the first portion con- 
tained 55.83 of acid in iOO parts, and another portion only 49.5 ; but 




£ 68 3 

it is far from improbable, that these salts were both mixtures of the 
acidulous sulphate, aiid the neutral sulphate of potash ; and the idea 
is strengthened by the circumstance, that he obtained neutral sul- 
phate from the same solution, towards the end of the process ; but^ 
even allowing the substances to have been principally simple binary 
combinations, and not mixtures, still the potassa and the acid may 
be regarded in them as in definite proportions. The number rcpre- 
aenting potassa being considered as 90, and that representing sul- 
phuric acid as 75, the first may be conceived to contain four of al- 
l^ali and seven of acid, and the second, three of alkali and four of 
acid. 

In cases m which solutions of salts are formed in acid or alkaline 
menstrua, which are supposed incapable of decomposing them> the 
results must be considered as depending upon a new combinatioD ; 
and in the evaporation of the water or of the menstruum, and the 
crystallization of the remaining constituents, the proportions, thai. 
have acted, will determine the nature of the solids which are form- 
ed. There appears no difficulty in reconciling the doctrine of defi- 
nite pix)portions, with the influence of quantity ; none of the expert- . 
ments of M. Berthollet can be considered as strictly contradictory to 
the doctrine, and some of the most important results of this saga- 
cious chemist afford it confirmation. 

18. M. Berthollet supposes that the attractions of bodies for each 
other, are inversely, as the quantities that saturate. Thus, magnesia 
and ammonia take up more sulphuric acid than equal quantities of 
potassa ; and therefore he concludes, that magnesia and ammonia 
have a stronger attraction for acids than potassa: yet potassa in- 
stantly separates magnesia and ammonia from acids; and though 
the facility with which ammonia is expelled from a compound, may " 
be hypothetically accounted for, by assuming that the ease, with 
which it takes the gaseous state, assists its escape ; yet magnesia is 
in an opposite case ; and to account for chemical changes, by sup- 
posing the effects of forms of matter, which are about to appear, or 
powers not in actual existence, such as elasticity or cohesion, is 
merely the solution of one difficulty, by the creation of another ; and 
ammonia, when solid oj* fluid, should require a new force to render 
it elastic : and the cohesion, in a compound, can only be regarded aB 



C 69 ] 

the exertion of the chemical attractions oF its elements. The action 
between the constituents of a compound must be mutual ; sulphuric 
acid, there is every reason to believe, has as much attracticMi for 
baryta, as baryta for sulphuric acid : and baryta is the alkaline sub- 
stance, of which the largest quantity is required to saturate sulphu- 
ric acid ; therefore, on M. Berthollet'9 view, it has the weakest affi- 
nity for that acid ; but less sulphuric acid saturates this substance* 
than any other earthy or alkaline body ; therefore, according to M. 
Berthollet, sulphuric acid has a stronger affinity for baryta, than for 
any other substance ; which is contradictory. 

1 9. It cannot be laid down as a general law, that the attractions of 
bodies are connected with the weights of the proportions in which 
they combine ; yet in some cases the proportions, wliich unite in the 
greatest quantity, or the bodies represented by the highest numbers, 
are separated by proportions combining in smaller quantity, or by 
bodies represented by lower numbers. Thus gold, platina, mercury, 
and silver, are separated in their metallic states by the common me- 
tals, which are represented by much lower numbers, and the metal- 
lic oxides by the alkalies ; but there are many exceptions ; and the 
intensity of attraction seems to be dependent upon other causes, 
which are intimately related to the electrical phaenomena, to be dis- 
cussed in the next section. 

30. The uniformity of the law of condensation, when gasses com- 
bine and form denser gaseous compounds, in which the volume is 
unaltered, or in which one of the elements is condensed to ^, or in 
which both are condensed to -J, and the regularity of the forms of 
solid bodies, seem to depend entirely upon the constancy of the na- 
ture of the combination, and probably upon the corpuscular aggre- 
gates being all of the same kind. If the particles of matter be sup- 
posed to be globular, or to act in spheres of attraction and repulsion, 
it would be easy to account for their forms, by supposing a few inde- 
pendent primary arrangements. Thus, four particles may compose 
a tetrahedron, five a tetraedral pyramid, six an octaedron, or a triedral 
prism, and eight, a cube or a rhomboid. 

21. It would be premature in this part of the work, to enter upon 
any more minute views of the laws of attracUon,^and the more refined V 



C 70 ] 

details vUl properly follow the history of the agencies of differcie 
bodies on each other. 

With respect to a power so constantly in action, it is necesMii^ 
however, even at an early period of the study, to possess some defr 
nite ideas. If it be regarded as capricious in its effects, and tOD^ 
ing constantly to produce different arrangements, chemistry wouU 
be without a guide, without certain combinations, and no results flf I \ 
analysis could be perfectly alike ; but fortunately for the progress of I 
science, this is not the case : the changes of the terrestrial cycle d\ c 
events, like the arrangements of the heavens, and the system of :di0 
planetary motions, are characterized by uniformity and simplici^; 
weight and measure can be applied to them, their order perceivei 
and their laws discovered. 



VII. .0/ Electrical Attraction and Refiulsion^ and their Relaiioiu t» 

Chemical Changes. 




1. If a piece of dry silk be briskly rubbed against a warm plats f^ 
polished flint glass, it will be found to have acquired the propeilf 
of adhering to it, which it will retain for some seconds ; if at tkl 
time this adhesive power exists, the silk and glass be separated froA 
each other, they will both be found to have gained the property d 
attracting very light substances, such as the ashes of paper or fa^ 
ments of gold leaf; and the long filaments of the silk, if there k 
any, will be seen to repel each other. 

2. These bodies are said to be electrically excited^ and the phaeuft' 
xnena are called electrical phsenomena ; the peculiar circumstance! 
under which they occur, are best observed by the use of an initn^ 
ment called the electrical machine ; it consists of a cylinder of glai' 
supported upon glass pillars, and which can be made to revolve^ tf 
as to press agsdnst a cushion of silk rubbed over with a little ami^ 
gam of zinc and mercury ; and of two cylinders of metal, one in ccfr 
tact wiih the cushion, and the other opposite to the glass cylinte 
both supported upon glass. 

3. If two gilt pith balls, suspended upon strings of silk covtt«d 
iith tinsel, be hun^ upon a wire, placed in contact with either of 

* Plate II. fig. 9. 



:i-..-.. 



[ 71 ] 

the metallic cjUndersy and the machine be put in action^ the balls 
will repel each other ; but if one ball be attached to a wire, connect- 
ed with one metallic cylinder, and the other ball be attached to a 
wire connected with the other, the two balls, when the machine is 
put into*action, will attract each other ; and at the moment that they 
come in contact, sparks of light will be perceived, if the experiment 
he made under favourable circumstances. 

As the two balls, when in contact with the same cylinder, may be 
considered as receiving the same impulse or impression, they are 
•aid to be nmilarly ehetrified; but when in contact with different 
cylinders, they are sdd to be differently electrified; and electrified 
bodies that repel each other, are considered as in the same electrical 
states; those that attract each other as in different electrical 
states. 

4. There are probably no two bodies differing in nature, which 
are not capable of exhibiting electrical phaenomena, either by con- 
tact, pressure, or friction ; but the first substances in which the pro- 
(lerty was observed, were vitreoue and retinoua bodies ; and hence 
Id&e different states were called states of reainoua and vitreous elec- 
tncity ; and resinous bodies bear the same relation to flint glass, as 
«yik. The terms, negative and fio*itive electricity, have been like* 
mse adopted, on the idea, that the phaenomena depend upon a pe« 
culiar subtile fluid, which becomes in excess in the vitreous, and de- 
ficient in the resinous bodies ; and which is conceived by its motion 
snd transfer, to produce the electrical phsenomena. 

5. Flint glass and silk, silk and sulphur, sulphur and metals, resin 
9aid metals, all by friction or contact, become strongly electrical, 
«nd of course attractive, and communicate their attractive powers to 
«niall masses of matter brought in contact with them ; a pith ball, or 
« slip of gold leaf that has been touched by flint glass, excited by 
silky will be repelled by a ball or slip that has been touched by silk, 
«xched by sulpur, or by a ball or slip that has been touched by sul« 
-^ur excited by metals, so that the attractive and repellent states de» 
pend entirely upon the actions of the two substances, and not upon 
any power peculiar to, and inherent in each. 

6. It is upon this circumstance, that the electrometerj which 

might be called the differential one, is framed ; it consists of two , l|( 



I 



C 72 3 

I 

gold leaves attached to a metallic plate, and included in a hcdlmr 
cylinder of glass*, fixed upon another mciaDic plate, which is can- I 
nected with two pieces of tin foil, pasted upon the glass opposite to 
the leaves. When any electrified body is made to touch the upper 
plate, the gold leaves diverge ; if their divergence is increased .by 
the approach of fiint glass excited by silk, they are said to have the 
same state as the glass, the vitreous or the positive ; if their divei^ 
gence is diminished, they are said to be in the opposite state, or to 
possess the resinous or ne(*;ative electricity. 

7. When luminous phaenomena are connected with electrical ez- 
citation, the different states may be known by presenting a metaliia 
point to the excited body ; if rays of light issue from the point to 
the body, it is said to be negatively electrified : but if the point ap" ' 
pears simply luminous, without sending off any rays, the electricity 
is said to be positive. 

8. For measuring small degrees of electricity of bodies, as com- • 
pared with those of others of the same kind, the electrical balance of 
Coulomb is applied; it consists of a gilt pith bail, placed upon ametalfic 
rod, on the opposite extremity of which, is a thin leaf of metal s tfad • 
rod is suspended horizontally, by a fine metallic wire, which pasaei 
into a glass tube, to the top of which it is attached ; the glass tube 
is inserted into a cylinder of glass, which contains a copper ball, con- 
nected with a small bar of metal, which is carried through an ape^ 
ture in the glass cylinder, into the atmosphere ; a very small forpe 
only is required to twist the wire, and when the two balls are brought 
in contact, and the bar touched by the electrified body, they gaa 
the same kind of electricity, and repel each other ; and the degfce 
of their repulsion may be measured by a scale of degrees, made oa . 
the circumference of the cylinderf. 

9. Bodies receive the electrical influence in different manners. If 
a rod of glass be brought in contact with any excited electrical bodyi 
it will receive the electrical influence in the part where it touched* the 
body, and will be electrical, to a little distance, round the point rf 
contact ; but its remote paits will not be aflected. A rod of metsli f 

• PUte II. fig. 10. t Plate II. fig. IL 



I 



[ 73 ] 

on the contrary, suspended on a rod of glass, and brought in contact 
with an electrical surface, instantly becomes electrical throughout. 
The glass, in common philosophical language, is said to be a non- 
conductor of electridty, or an insulating substance ; the metal a con- 
ductor. Some bodies are affected to a much greater extent than 
glass, but not nearly so much as metals ; such are animal and vege- 
table substances, water, and fluids containing water; they are said 
to be imperfect conductors. According to the statements of Mr. 
Cavendish, iron conducts 400 millions of times better than ^vater, sea 
water 100 times better tlian distilled water, and water saturated with 
salt, 720 times better. The mineral acids are tlie best fluid conduct- 
ing substances known, and after them, saline solutions, the powers of 
which appear to be nearly in proportion to the quantities of salts they 
contain. Charcoal and metals, and the greater number of inflamma- 
ble metallic compounds, are conductors. Alcohol and ether arc 
very imperfect conductors; and sulphur, oils, resinous substances, 
metallic oxides, and compounds of chlorine, nonconductors. 

10. There is a stone found in many parts of the world,- called 
tourmaline, which is sometimes crystallized as a nine-sided prism, 
terminated by a three-sided and a six-sided pyramid ; when this sub- 
stance is gently heated, it becomes electrical, and one cxtrenuty, that 
terminated by the six-sided pyramid, is positive, the other is negative ; 
to a certsdn extent, its electricities are exalted by increasing tlie tem- 
perature ; when it begins to cool, it is still found electrical ; but the 
electricities are changed, the pyramid, before positive, is now nega- 
tive, and vice versa. When the stone is of considerable size, flashes of 
light may be seen along its surface. 

There are other gems and crystallized substances, which possess 
a property similar to that of the tourmaline. The luminous appear- 
ance of some diamonds, when heated, probably depends upon their 
electrical excitation. The substance called the boracitc, which Ls 
a cube, having its edges and angles defective, becomes electrical by 
heat, and in one variety presents no less tlian eight sides, in diflcr- 
ent states, four positive, four negative ; and the opposite poles arc 
in the direction of the axes of the crystal. 

1 1. It would appear, that in all cases of electrical action, the two 
electrical states are always coincident, cither in different parts of the 

K 



[ 74 ] 

same body, or in two bodies ; and tliat they arc always equal, and 
capable of neutralizing each othRr. If a connection be made by a 
wire, between the positive and negative conductors of the electrical 
machine, during the time of its action, all electrical effects cease ; 
and to produce a succession of effects, both conductors must be ; 
brought near bodies connected with the ground, which gain the ' 
opposite state, in consequence of what may be called induction, and i 
which will be explained in the next paragraph. j 

12. When a nonconductor, or imperfect conductor, provided it be I 
a thin plate of matter, placed upon a conductor, is brought in con- \ 
tact with an excited electrical body ; the surface, opposite to that io 
contact, gains the opposite electricity from that of the excited body; 
and if the plate be removed from the conductor and the source of 
electricity, it is found to possess two surfaces in opposite states. If 
a conductor be brought into the neighbourhood of an excited body, ; 
the air, which is a nonconductor, being between them ; that extremi- | 
ty of the conductor, which is opposite to the excited body, gains the j 
opposite electricity, and the other extremity, if opposite to a body i 
connected with the ground, gains the same electricity, and the 
middle point is not electrical at all. This is easily proved, by ex- 
amining the electricity of three sets of gilt pith balls raised on wires 
on the different parts of the conductor, which is thus affected by 
induced electricity. 

If, instead of air, a plate of mica or glass be between the two con- 
ductors, the same phaenomena will occur ; so that it would appear 
that the conductor merely g^ins two opposite electricities, or polar 
electricities, of the same kind as those of the nonconductor. The 
phaenomena of sparks, of discharges, and of accumulated electricity, 
depend upon this law. In the case of the common electrical spark, 
a stratum of air is charged in the same manner as a glass bottle, 
partially coated with tin foil, is charged in the Leyden experiment* ; 
when the hand is held near the positive conductor of an electrical 
machine, the person standing on the ground, the hand is rendered 
negative, and the states become exalted, till the polarities, as they 
may be called, are annihilated through the air, producing a sparjk, 

• Plate II. fig. 12. 




C 75 ] 

.. a snap, and a distinct sensation. If a number of small pith balls^ 
placed upon a surface of metal, are caused to approach an electrified 

: body, they are brought into the opposite state by induction, and are 

, attracted towards the body ; but when they come in contact with it, 
this state is destrojed, they gain the same state, and are repelled ; 
and if they are pM^rly placed, their alternate attractions and re- 

.-' pulsions may be produced, as long as the machine is in action. 

13. If a number of cylinders of metal, insulated on glass, be 
\ placed in a line with each other, but not in contact, and the last be 
: connected with the ground* ; when a powerfully electrified conductor 
y of a machine is brought opposite to the hrst, they will all become 
: electrical, and every insulated cylinder will present two poles; the 
^ negative pole of one being opposite to the positive pole of the other ; 

and if a spark is produced by means of the last, sparks occur 
throughout the whole arrangement. In like manner a series of 
Leyden jars may be made to charge each other, the outer surface of 

: the first rendering negative tlie inner surface of the second, and so 
on ; and by connecting the surfaces, tliat have the same kind of 

-_ electricity, in the first place, and then connecting two opposite sur- 
faces in the series, a powerful cxplosionf may be produced. 

1 4. When a point connected with the ground, is brought near an 
electrified substance, it rapidly gains the opposite state, and an im- 
mediate discharge takes place, which continues till the equilibrium 
is restored. Large surfaces are electrified by induction much more 
slowly than small ones, and are capable of accumulating much more 
electricity ; which renders the discharge from them much more vio- 
lent. Indeed the electrical powers seem entirely to belong to the 
sur^ces of bodies, and not to be connected with the quantity of solid 
matter they contain. 

15. It is in consequence of the principle of induction, that the con, 
densing electrometer is so much more sensible than the common 
electrometer ; this instrument consists of two plates of polished me- 
talf, the surfaces of which are parallel, one connected with the plate 
of the electrometer, the other moveable, in connexion with the 
ground, and the plates are very near each other. When the body 

» Plate III. fig. 13. t Pl*te III. fig. 14^ X Plate III. fig. 15, 



[ 76 ] 

supposed to be electrical, is made to touch the top of tlie electronic^ 
tor, and is afterwards removed, in separating the plates, the effect 
will be perceived. 

1 6. The difference in what arfc called the conducting powers of 
bodies, seems to depend entirely upon the different manner in wMch 
they receive the electrical polaiities, or in which-flieir parts become 
' capable of communicating attractive or repellent powers^ to other 
matter. Nonconductors appear to receive polarities, only with great 
difficulty, but retain them for a long while, and present probably a 
number of different alternations of poles, within a small space^ .and 
cannot be effected to any great distance. Imperfect conductors re* 
ceive polarity with more facility, but present fewer alternations, and 
preserve their electricities for a shorter time. Perfect conductors 
are easily effected throughout; but present at most only two poles, 
and the powers rapidly destroy each other. The difficulty with whidi 
nonconductors receive polarity, is shewn in the phaenomena of charg- 
ing tliick and thin coated plates of glass and mica. The thin plates 
are capable of being charged much more highly than the thick ones^ 
and the accumulation on the opposite surfaces is much greater. 

Rarefied air or gaseous matter, is much more susceptible of re- 
ceiving polarities, than dense air or gaseous matter; and hence, the 
electrical spark will pass much further through rarefied air or light 
gasses, than through dense air or heavy gasses; it passes much fur- 
ther likewise in gasses, than in nonconducting fluids. 

ir. If a nonconducting surface, coated with two conducting 8^I^ 
faces, and charged so as to give a spark of an inch m length, through 
air, be connected by both its conducting surfaces, with a similar ap- 
paratus not charged; then both systems maybe discharged together; 
but tlie spark they will give, will be only half as long as the single 
one would have given, if discharged alone. The quantity of the 
electricity in this case, is conceived not to be altered, but its intend' 
ty is said to be only half as great when it is discharged from a dou- 
ble surface ; and these expressions of intensity and quantity, though 
it is not easy to attach any very definite ideas to them, are neverthe- 
less useful, in giving more facility to the arrangement of some im- 
portant electrical phaenomena. 




[ 77 ] 

1 8. When very small conducting surfaces are used for conveying; 
f very larg^e quantities of electricity, they become ignited ; and of the 
different conductors that have been compared, charcoal is most easily 
\ heated by electrical discharges*, next iron, platina, gold, then cop- 
: per, and lastly zinc. The phenomena of electrical ignition, ^vhcther 
J taking place in gaseous, fluid, or solid bodies, always seem to be the 
l' result of a violent exertion of the electrical attractive and repellent 
!> powers, which may be connected with motions of the particles of the 
:' substances affected. That no subtile fluid, such as the matter of heat 
: has been imagined to be, can be discharged from these substances, 
in consequence of the effect of the electricity, seems probable, from 
i the circumstance, that a wire of platina may be preserved in a state 
- of intense ignition in vacuo, by means of the Voltaic apparatus, (an 
r instrument which will be immediately described,) for an unlimited 
. time ; and such a wire cannot be supposed to contain an inexhausti- 
:' ble quantity of subtile matter. 

f 19. Certain changes in the forms of substances, ai*e always con- 
, nected with electrical effects. Thus when vapour is formed or con- 
:. densed, the bodies in contact with the vapour, become electrical. If; 
^ for instance, a plate of metal, strongly heated, be placed upon an 
k electrometer, and a drop of water be poured upon the plate, at the 
moment the water rises in vapour, the gold leaves of the electrome- 
ter diverge with negative electricity. Sulphur, when melted, be- 
comes strongly electrical during the time of congelation ; and tlic 
case seems to be analogous, with respect to nonconducting substances 
in genenil, when they change their forms. 

20. As electricity appears to result from the general powers or 
agencies of matter, it is obvious, that it must be continually exhibit- 
ed in nature, and that a number of important phsenomena must de- 
pend upon its operation. When aqueous vapour is condensed, the 
clouds formed are usually more or less electrical ; and the eaith be- 
low them being brought into an opposite state, by induction, a dis- 
charge takes place when the clouds approach within a ceilain dis- 
tance, constituting lightning; and the undulation of the air, produced 

* The conclusions are drawn from experiments made by the electricity of the 
Voltaic apparatus. 



C 78 ] 

by the discharge, is the cause of thunder, which is more or less in- 
tense, and of longer or shorter duration, according to the quantity of 
air acted upon, and the distance of the place where the report ii 
heard from the point of the discharge. It may not be uninteresting 
to give a further illustration of this idea: electrical effects take place 
in no sensible time ; it has been found, that a discharge through i 
circuit of four miles, is instantaneous; but sound moves at the rate of 
about twelve miles in a minute. Now, supposing the lightning to past 
through a space of some miles, tlie explosion will be first heard frwn 
the point of the air agitated, nearest to the spectator ; it will gradually 
come from the more distant parts of the course of the electricity, ani 
last of all, will be heard from the remote extremity ; and the differ-, 
cnt degrees of the agitation of the air, and likewise the difference of 
the distance, will account for the different intensities of the soundi^ 
and its apparent reverberations and changes. 

21. In a violent thunder storm, when the sound instantly succeeds 
the flash, the persons who witness the circumstance are in some 
danger ; when the interval is a quarter of a minute, they are secure-. 
In a thunder storm, the lowest ground is the safest place, and a hori- 
zontal posture, the least dangerous ; the neighbourhood of treesy or 
buildings, should be avoided, particularly of trees, the living juices 
of which are calculated to conduct tlie electricity, and make part of 
a circuit. In a house, the cellars are the safest places, and in a room 
the person should stand as far as possible from the fire. The meam 
adopted by Franklin have, however, to a great extent, aV^erted the 
destructive effects of atmospheric electricity; and by pointed ccmduc- 
tors, the thunder cloud is disarmed of its terrors, and the lightning 
slowly discharged in harmless corruscations. 

If a school-boy's kite be mounted high in the atmosphere^ by 
means of a string, containing filaments of metal, fastened to a con- 
ductor, fixed on a glass rod ; the conductor usually gives signs d 
electricity, which will be greatest, when clouds are floating in the 
atmosphere ; and it was by means of a simple apparatus of this kind, 
that the American philosopher effected his grand discovery of the 
identity of electricity and lightning. 

Thyiyer-spout is probably the result of the operation of a weakly 
eler '^J|od, at an inconsiderable elevation above the sea, brought 




C 79 ] 

"■ into an opposite state ; and the attraction of the lower part of tlie 
" cloud for the surface of the water, may be the immediate cause of 
this extraordinary phenomenon. 

The corruscations of the aurora borealis and australis, precisely 

'- resemble strong artificial electricity discharged through rare air ; 

~; and as the poles are nonconductors, being coated with ice or snow, 

"^ and as vapour must be constantly formed in the atmosphere above 

y them, the idea of Franklin is not improbable, that the auroras may 

-,/ arise from a discharge of electricity, accumulated in the atmosphere 

V» near the poles, into its rarer parts ; though other solutions of the 

• phaenomena may be given on the idea, that the earth itself is endow- 

■\'ed with electrical polarity ; or tliat the motions of the atmosphere 

; produce the effect : but all views on this subject must be hypothe- 

.' tical, and the light may result from other causes than electrical 

-' action. 

22. The common exhibition of electrical effects is in attractions 
"'and repulsions, in which masses of matter are conccmed; but there 
-' 'are other effects, in which the changes that take place operate in a 
'" .manner, in small spaces of time imperceptible, and in which the 
effects are produced upon the chemical arrangements of bodies. 
If a piece of zinc and a piece of copper be brought in contact with 
^^ each other, they will form a weak electrical combination, of which 
~ the zinc will be positive, the copper negative ; this may be learnt by 
the use of a delicate condensing electrometer ; or by pouring zinc 
filings through holes, in a plate of copper, upon a common electro- 
^ meter ; but the power of the combination may be most distinctly 
. exhibited in the experiments called Galvanic exfieriments^ by con- 
necting the two metals, which must be in contact with each other, 
with a nerve and muscle in the limb of an animal recently deprived 
of life, a frog for instance ; at the moment the contact is completed, 
or tlie circuit made, one metal touching the muscle, the other the 
nerve, violent contractions of the limb will be occasioned. If a piece 
of zinc or copper, in contact with each other in one point, be placed 
in contact in other points with the same ponion of water ; the zinc 
will corrode and attract oxygene from the water, much more rapidly 
than if it had not been in contact with the copper ; and if a small 
quantity of sulphuric acid be added to the water, it will be seen tliat 



\ 




C 80 ] 

globules of inflammable air are given off from the copper, though it 
is not dissolved nor acted upon. 

23. The connection of chemical effects, with the exhibition of 
electrical powers, is, however, best witnessed in combinations in 
which these powers are accumulated by alternations of different me- 
tals and fluids. If plates of copper and zinc, two or three inches 
square, and pieces of cloth of the same size, soaked in a solution of 
salt, or sal ammoniac, or nitre, be arranged in the order of copper, 
zinc, moistened cloth, and so on, and made into an insulated pile, oT 
which the series arc 200*, several remarkable phaenomena viD 
occur. 

When one hand is applied to the bottom of the pile, and the other 
to the top, both hands being moistened, a shock will be perceived. 

When a metallic wire, having a bit of well-bumed charcoal at its " 
extremity, is made to connect the two extremities of the pile, a spaA 
will be perceived, or the point of the charcoal will become ignited. 

A wire connected with the top of the pile, brought in contact wiA 
a sensible electrometer, will cause the leaves to diverge ; and, bf 
removing the wire, and applying excited glass to the electrometer} 
it will be found that the electricity is positive ; a wire connected with 
the bottom of the pile will affect it with negative electricity ; a wire 
from the middle of the pile will have no influence on the instn- 
ment. 

If wires of platina from the extremities of the pile bo introduced 
into water, or ijato two portions of water connected by moist substan- 
ces, oxygcne gas will separate at the wire exhibiting the positive 
electricity, and hydrogcne gas at the vnre exhibiting the negative 
electricity ; and the proportions are siich, when the proper circum- 
stances exist, that they will produce water when exploded by the 
electrical spark, tliat is, the volume of hydrogene will be to that of 
ox y gene as two to one. ■ 

If the same wires be introduced into a strong solution of sulphu- 
ric or phosphoric acid, or into metallic solutions, oxy gene v<^ill sepa- 
rate at the positive surface, the inflammable or m.etallic matter con- 

y^cd in the solution at the negative surface. 

" See Plate III. fig. 15, 16. 



C 81 ] 

When any substance tendered fluid by heat, consisdng of water^ 
oxyg^ne, and inflammable or metallic matter, is exposed to those 
wires, similar phaenomena occur. 

When any solution of a neutral salt containing acid, united to al- 
kaline, earthy, or common metallic matter, is used; besides the 
other phaenomena that take place, acid matter collects round the 
positively electrified surEice ; alkali, earth, or oxide, round the ne- 
gative surface ; and if two separate vessels are employed to contain 
the solution, connected by moist asbestus, it is found, that the acid 
collected in the vessel containing the wire positively electrified, will 
be in definite propoition to the matter collected in the other cup ; 
that is, it will form with it a neutrosaline compound. 

If a solution of muriatic acid in water be acted on by the wireSf 
hydrogene will separate at the negative surface, and chlorine or oxy- 
muriatic gas, at the positive surface. 

24. This apparatus, which exhibits in so distinct a manner the 
relations of electrical polarities to chemical attractions, is the grand 
invention of Volta, made known in the first year of this century ; its 
electrical eflects have been long known, but the phaenomena of its 
operation in decomposing bodies are of more recent discovery. 

Several modes of constructing it have been adopted, some of 
which are much superior, in point of convenience, to that which has 
been just described. 

One mode is by soldering the plates of zinc and copper together) 
and by cementing them into troughs of baked wood, covered with 
cement, in the regular order, so as to form cells to be filled with the 
fluid menstruum ; each surface of zinc being opposite to a surface 
of copper ; and this combination is very simple and easy of applica- 
tion. 

Another form is that of introducing plates of copper and of zinCf 
fastened together by a slip of copper, into a trough of porcelain, con- 
taining a number of cells corresponding to the number of the series. 
The different series may be introduced separately into the troughs, 
and taken out without the necessity of changing the fluid, or they 
may be attached to a piece of baked wood, and (when the number is 
not very large) introduced into the cells, or taken out together*. 

• Plate IIL fig. 17. 

L 



[ 82 i 

25* Similar polar electrical arrangements to those formed by zinc 
and copper may be made by various alternations of conducting and im« 
perfect conducting substances ; but^ for the accumulation of the 
power, the series must consist of three substances or more, and one 
at least must be a conductor. Silver or copper, when brought in 
contact with a solution of a compound of sulphur and potassa, at one 
extremity, and in contact with water, or a solution of nitric acid, at 
the other extremity, some saline solution being between the suJphu^ 
retted and the acid solutions, forms an element of a powerful combi* 
nation, which will give shocks when fifty are put together; the order 
is copper, cloth of the same size moistened with solution of nitric 
acid, cloth moistetied in solution of common salt, cloth moistened in 
solution of the compound of sulphur, copper, and so on ; the specie 
gravities of the solutions should be in the order in which they vie 
arranged, to prevent the mixture of the acid and sulphuretted solu* 
tion ; that is, the heaviest solution should be placed lowest. 

The tables annexed contain some series, which form Voltaic el€(> ; 
trical combinations, arranged in the order of their powers ; the sub* 
stance most active being named first in each column. 

Table of some Electrical JlrrangementSy ivhichy by Combination j/brm 
Voltaic Batteries^ comfiosed of two Conductors^ and one imficrfect 
Conductor. 



Zinc 

Iron 

Tin 

Lead 

Copper 

Silver 

Gold 

Platina 

Charcoal 



Each of these is the positive pole to 
all the metals below it, and negative 
with respect to the metals above it in 
the column. 



Solutions of nitric acid 

of muriatic acid 
of 8ul|^uric acid 
of sal-anunomac 
of nitre 
other neutral salts 



S 



C 83 3 

Table q/'9ome Electrical Arrangements^ consisting ^f one Conductor 

and two imfierfect Conductors, 



Solution of sulphur and potash 


iCopper 


of potash 


Silver 


of soda 


Lead 




Tin 




Zinc 




other metals 




Charcoal 



Nitric acid 

Sulphuric acid 

Muriatic acid 

Any solutions containing acid 



The metals having the strongest attraction for oxygene are the 
metals which form the positive pole, in all cases in which the fluid 
menstrua act chemically by affording oxygene ; but when the fliud 
menstrua afford sulphur to the metals, the metal having the strong* 
est attraction for sulphur under the existing circumstances, deter* 
mines the positive pole ; thus in a series of copper and ircm, intro* 
duced into a porcelain trough, the cells of which are filled with 
water or with acid solutions, the iron is positive, and the copper ne- 
gative ; but when the cells are filled with solution of sulphur and 
potash, the copper is positive, and the iron negative. 

In all combinations in which one metal is concerned, the surface 
opposite the acid is negative, that in contact with solution of alkali 
and sulphur, or of alkali, is positive. 

26. The energy of a combinaticxi to give repulsive or attractive 
powers to masses pf matter, or to affect the electrometer, seems to 
increase with the number of the series, as does the power to give 
shocks, and to decompose bodies ; but as long as the surface of the 
gold leaves in the electrometer, or of the human body, or of the wa- 
ter acted upon, is the same, and less than that of the acting plates, 
increase of surface of the plates is connected with no increase of 
^ower. In the operation upon metallic substances or charcoal, or 
upon good imperfect conductors, the case, however, is different. 
Thus, though a battery composed of plates of copper and zinc a foot 
square, will not affect the condensing electrometer more, nor de- 
compose more water,^nor give greater shocks to the fingers, than a 
battery containing plates of an inch square, yet it will ignite more 
than 100 times as much fine piatina wire^ and decompose sulphuric 



[ 84 3 

acid, and the water in strong saline solutions, with infinitely more ra- 
pidity. This has been expressed by Mr. Cavendish in the state* . 
mcnt, that the intensity is the same in both cases; but that the 
quantity is in some ratio as the surface. The quantity in the small 
plates is as much or more than such imperfect conductors as water 
and the human body can carry oflf by a small surface ; whilst better 
conductors can transmit the whole quantity afforded by the large 
plates, even when used in very, thin laminae or wires. The correct- ■ 
ness of this view may be shown by a very simple experiment. Let . ; 
two platina wires, from the extremities of a battery composed of _ j 
plates of a foot square, be plunged into water, the quantity of gas i 
disengaged from the wires will be nearly the same as from an equal 
number of plates of an inch square ; let the fingers of each handy 
moistened with water, be applied to the two extremities of the bat- 
tery, a shock will be perceived nearly the same as if there had been , 
no connection between the wires and the water. Whilst the circuit 
exists through the human body and through water, let a wire attach- 
ed to a thin slip of charcoal be made to connect the two poles of the \ 
battery, the charcoal will become vividly ignited. The water and 
the cmimal substance discharge the electricity of a surface, probably 
not superior to their own surface of contact with the metals ; the 
wires discharge all the residual electricity of the plates ; and if a si- 
milar experiment be made on plates of an inch square, there will 
scarcely be any sensation, when the hands are made to connect 
the ends of the battery, a circuit being previously made through 
water ; and no spark when charcoal is made the medium of connec- 
lion, imperfect conductors having been previously applied. 

The first distinct experiment upon the igniting powers of large 
plates was performed by M. M. Fourcroy, Vauquelin, and Thcnard 
But the grandest combination ever constructed for exhibiting the 
effects of extensive surface, was made by Mr. Children : it consists 
of twenty double plates four feet by two ; of which the whole sur- 
faces are exposed, in a wooden trough, in cells covered with cement^ 
to the action of diluted acids. This battery, when in full action, had 
no more effect on water or on the human body than one containing 
an eq ual_n umber of small plates ; but when the circuit was made 
thr<»^^5Ht*^^^ wires, the phaenomena were of the most brilliant; 



/ 



f 



[ 85 ] 

^ind. A platina "wire of one thirtieth of an inch in thickness, and 
eighteen inches long, placed in the circuit between bai*s of copper, 
nstantly became red hot, then white hot, the brilliancy of the light 
ras soon insupportable to the eye, and in ^a few seconds the metal 
ell fused into globules. The other metals were easily fused or dis- 
i{>ated in vapour by this power. Points of charcoal ignited by it 
iroduced a light so vivid, that even the sunshine compared with it 
ppeared feeble. 

Mr. Children has another battery in construction, the plates of 
irliich are double the size of that just described, and which are to be 
rranged in pairs in single troughs, and connected by means of plates 
f lead in regular. order. 

27. The most powerful combination that exists in which number 
f alternations is combiaed with extent of surface, is that constructed 
y the subscriptions of a few zealous cultivators and patrons of sci- 
nce, in the laboratory of the Royal Institution. It consists of two 
undred instrumentsj connected together in regular order, each 
omposed of ten double plates arranged in cells of porcelain, and 
Dntaining in each plate thirty-two square inches ; so that the whole 
umber of double plates is 2000, and the whole surface 128000 
juare inches. This battery, when the cells were filled with 60 
arts of water mixed with one part of nitric acid, and one part of sul- 
huric acid, afforded a series of brilliant and impressive effects. 
V'hen pieces of charcoal about an inch long and one sixth of an inch 
I diameter, were brought near each other (within the thirtieth or 
•Ttieth part of an inch), a bright spark was produced, and more 
i.an half the volume of the charcoal became ignited to whiteness, and 
r withdrawing the points from each other a constant discharge took 
Lace through the heated air, in a space equal at least to four inches, 
reducing a most brilliant ascending arch of light, broad, and coni- 
U in form in the middle*. When any substance was introduced 
ito this arch, it instantly became ignited ; platina melted as readily 
I it as wax in the flame of a common candle ; quartz, the sappliire, 
lagnesia, Ume, all entered into fusion ; fragments of diamond, and 
Dints of charcoal and plumbago, rapidly disappeared, and seemed to 

• Plate III. fig. 1& 



[ 86 3 

t-k'i^tunct J3k t:- r« ec v bes :bf coecxrraiic v £s made im a n 
<ijxai:si"«ii be tbc iir paE^; bnt ihcrt -wa lo fvidcDcc of tic 

WbcE ibt crrr.7BiTTflrA.-ix, berween ibt paazni^ pofcinvfJr and 
•d^crr ejecriaed irjt* made id mt*. Tiirt Sec e Tie receiver of i 

tiif txhrcfibcjii ir£i TTflfif^ £Dd whiTL "Lbc armospbcTf is liic 
*r.Ti"Dor:ii cttjj Dot iiKS'^ii of zn incr cc mtTTurr in ibe hsran 
p:^:, tb? ijKJt* pii5i5»cc xbrcnich z space a: nta^rnr htoVT sii jud 
W villi irLvhi^ tbt pDiin*. frwi. cecL oiher, ibt fecharpe- wb 
i:.Tz*'^£:'L sih: or sfvt'L ioch'js^ prcidncinir * mos: beELnnfuI ooi 
-J3i! of pcrpje iig^b:- the charcaiJ btcame imssisch- irnheiL wai 
piicinL ^'ire ictLrbe^ to ii. f uik-^ mxxi brilliaTit ftciiniils=iaD&, i 
in lErrt «;j6hii]« npcm ibe plaxt of the puitp. All "die pbzo 
fjf cn?rm?rAi ds^composiiazi vere produccf vhb imense nfa 
T>^w; comliTHiriari. TThezi the poxntb of cbkrcosu vcre braii|^ 
earh orber ixi iiaDr:iDdur±ng fiizid&. such a^ oils. eriier« and e 
riariL compouDds. bnOimit spicks or.rurrEtd. soil eiBBtic suit 
Taiiidh- ccneraied ; sdg such fras the inifaisirr nf the dectnoil 
Sparks vere prodaced. evLii in g^Dod imperfer. couductors. s 
th; nitric and su)phnnc acids. 

When thf two conductors f-om liif ends of tbt comhiiiHtia 
cnnnerred vith ii Lryden banerr. one vitr. ihf imenuil, tbc 
vi:i. the cja^md caatiii^. tht bonerv iiisurniir hecame d 
and cm rnncvinp *ht wires, and icLking uk proper camD 
eh^«:T £ r.hork or h. spark coulfl he percei^rc ; and the least 
bU- VLna of ccimad was scfucicni it- renew tbf charct: to its i 
Tcnsh} . 

i?S. The- rrcncml fact** of the connecuan of the increase oft 
fv 'Tn: pC'Vert. of :br ba::tT\- wj-Ji -the iiicrrjiae of The Bumfai 
sirfurj f.f i:k siVk-s;. art vrrv disdnr: ; bt: ir- determine the 
•.::'i ofrht connr.:i:in i* i^pmbkir no: easy o' soiunon. 

M M. G:iv Luiisur anc Thcnarcl htv- announced, tha: the 

.1; r.kT:ir.ul cioc'iir.pn-YJ.iim inv/.Tujics onjv uj- ihe rube root 

1 .rniK-i <)• p:;:;- ; bu: \hv'.': r\pc::iTirr.> veT mafk wiih p 

r.:u> ot ;. cons: vi>. -ion vi :a unLvou'-anii fn: rainiiiir accur 

: uni; ii. Vi.rn.ii< :-;•..:> made vi-.r. p^-i; cart in the labora 



C 87 ] 

^ Royal Insdtution, the results were altogether different. The 
iteries employed were parts of the great combination^ carefully 
ulated, and similarly charged ; arcs of zinc and silver presenting 
kial surfaces^ and arranged in equal glasses filled with the same 
id of fluid, were likewise used ; and the tubes for collecdng the 
sses were precisely similar, and filled witli the same solution of 
:as8a*. In these experiments ten pairs of plates produced fifteen 
iasures of gas; twenty pairs in the same time produced forty- 
lc : again, ten pairs produced five measures ; forty pairs in the 
ne time produced seventy-eight measures. In experiments made 
:h arcs, and wluch appeared unexceptionable, four pairs produced 
i measure of gas ; twelve pairs in the same time produced nine 
1 -^ of gas ; six pairs produced One measure of gas ; thirty pairs, 
der like circumstances, produced 24.5 measures ; and these 
UDtities are nearly as the squares of the numbers. 
It would appear from the experiments of Vanmarum and Pikif, 
ifirmed by those of Messrs. Wilkinson, Cutlibertson, and Singerf 
t the increase of power of batteries, the plates of which havo 
lal surfaces, is as the number. I found that ten double plates, 
h having a surface of a hundred square inches, ignited two inches 
platina in wire of one eightieth of an inch ; twenty plates, five 
hes ; forty plates, eleven inches ; but the results of experiments 
iiigher numbers were not satisfia.ctory ; for one hundred double 
tes of thirty-two square inches each, ignited three inches of pla- ^ 

31 wire of one seventieth, and one thousand ignited only thiiteen 
hes, and the charges of diluted acid were similar in both cases. 
The power of ig^tion for equal numbers of plates, seems to in- 
case in a very high ratio with the increase of surface, probably 
;her than even the square ; for twenty double plates, containing 
ih two square feet, did not ignite one sixteenth as much wire as 
enty, containing each eight square feet, the acid employed being 
the same strength in both cases. 

(Numerous circumstances are opposed to the accuracy of experi- 
tnts, made with high numbers, or very large surfaces; tlie activi- 
Df combinations rapidly diminishes in consequence of the decom- 

• Plate IV. fig. 19. 



« 



Tf'MJrzjcyr 'JC 



» l^*fnSa!7*l.'I^L l."i»*!l - Llit "H-S- \£''ZZi 



£'A vxirjnzji- 7*in?*:. iziz ".it rt* 17 13 ^nzr. :t :^ 



rr. i v'jojt zi'j.c. ~ i* r^r-LT r<:?iiu!:'j± t:: ■»"ilt -nsa^ i^rr of the 

■■-C virt- "lilt :"X'Zi:? ii^ii^-UTi if "-I't- s::j:T?*i:.ff ii. r-ri!m-t,r^^ jgH 
'' . "-V "^sn i-f •-i* dsiii iiw: ir^ji-pi- izr-tritrr*' — .~tKr- -vz^i 
"Jii'^r Off TT.rt irt «E"^}jprtc irii "rrii :'t*:ijt T^i-iPirs : : 

I: -.Ta*:* :i ir \n.ytrz^v. 'jyiryt-TrT ii. lz:t ■:: ii»» «^«». a ^^ctf 
—".-->->:: ■-: P--W*: ii ijc ri-iAtc -£--•: e- If yii* pint is ^.. ' jimi dB^ 
cv. t.'t-.i "»iiix Hi- -7* iiiir ibiT. ijj* r=:5^ "ihtTt 2** ecE^nl Iq»i 
tz-rn I: cLiprr ii Va-:;5dr-:*-c f:r ztj:- :.r mr fer o&pperi 
ini-It M::^r5- ±* rc-i-L:: ii *-—->-: i^ii i £7^ -j^i;:: ^ p'ti^-r^ win 
"iroi-crd i^ ibe pi&rr -jf izj i7^ o: &L1t£t ixii riiic- 19 £ 
ihiriT-. dl=±ii=i*tc! h> poller of prjii^cir.? rii *:. iziuch, siiitkl* 
e-. uii': orJv to ihi: of fjLr. 

->. Tit circ--*Tr!*>:iif:t =»>: iniTK-riLr: zzi tleirriccy, perlnpii' 
i:i cor-:?frr"i:a "»rLh ibe crieTTiical po^w^trs cf lEintr. aad tbc JOMtf 
in "w-bkhiiraoiiSfs, e3txJt&. or de-s^r^i-s ibsst pD-^ers. ytoAdLU 
idbstiijcts th^i an disdnctiT upoo ei:h oiber eieciricallv, uc]ik^ 
^ise such as 2c: chemicalir, when ih^ir particles haT« ficcdon'. 
mjiion : ihis Is the cise viih ibe oiffrreL: iDciiJs* iriih sulplnrirf 
;hc metals. wl:h acid :uid tlkaliire iur:si2cres: £Dd ihe reladfltf ' 
ix>Jics arc uniform ; those :ha: have the ii^bcs atxractizig pofCR 
l/cinc: i» the rcjation of pof^iuvc. iri arr-iu^cnDe::-^ in which chemki 
chur.c«^s c^n go on. Thus, sf i> shcTtrr. iu -Jie rabies, p&.ge 82, li* 
is po>::ivo wiih respect to iron, irc^rs T*::h re^pc-ct to copper, coppA 
respect 10 aihcr, and so on in :^ cosibiniiions in which csf 





s 

Cl 

n 

t 

p 

a 

ti 



[ 89 ] 

g^ne is capable of being combined with the metal; but copper is 
positive with respect to iron in compound menstrua containing sul- 
phur; the electrical power being in all cases apparently connected 
with the power of chemical combination. 

Crystals of oxalic acid touched by dry quick-lime exhibit electri- 
cal powers; and the acid is negative) the lime positive. 

All the acid crystals, upon which I have experimented, when 
Louched by a plate of metal, render it positive. And in Voltsdc com- 
>inations with single plates or arcs of metal, as is stated in pag^ 
3 3, the metal is negative on the side opposed to the acid, and posi- 
;ive on the side or pole opposed to the alkalL 

Bodies that exhibit electrical effects previous to their chemical 
i.ction on each other, lose this power during combination. Thus, 
C a polished plate of zinc is made to touch a surface of dry mercury; 
tnd quickly separated, it is found positively electrical, and the ef- 
^ct is increased by heat ; but if it be so heated as to amalgamate 
^th the surface of the mercury, it no longer exhibits any marks of 
electricity. The case is analogous with copper and sulphur ; and 
i*on acts more powerfully than zinc with quicksilver in a permanent 
electrical combination, as in the experiments of Colonel Haldane ; 
apparently, because under common circumstances it is incapable of 
amalgamating with that metal. When any conducting substance, 
::apable of combining with oxygene, has its positive electricity in- 
creased, it will attract oxygene with more energy from any imperfect 
conducting medium ; and metallic bodies that in their common state 
have no action upon water, such as silver, attract oxygene from it 
easily, when connected with the positive pole in the Voltaic circuit ; 
and bodies that act upon water, such as zinc and iron, so as to de- 
compose it slowly, refuse to attract oxygene from it when they are 
negatively electrified in the Voltaic circuit. 

Acids, which are negative with respect to alkalies, metals) and 
earths, are separated from these bodies in the Voltaic circuit at the 
positive sur^sice ; and alkalies, metals, and earths, are separated from 
acids at the negative surface : and such are the attracting powers qf 
these sur&ces, that acids are transferred through alkaline solutions, 
and alkalies through acid solutions, to the surfaces where they have 
their points of rest. It is easy to shew this by making a combina- 



[ 90 ] 

tion of three agate cups*, one containing sulphate of potassa, one 
weak nitric acid, and the third distilled water, and connecting them 
by asbestus moistened in pure water, in such a manner, that the 
surface of the acid is lower than the surface of the fluid in the other 
two cups. When two wires of platina from a powerful Voltaic 
apparatus are introduced into the two extreme cups, the solotioa 
of the salt being positively electrified, a decomposition will take 
place, and in a certain time a portion of potassa will be found dis- 
solved in the cup in contact 'with the negative wire, though the flind 
in the middle cup will still be sensibly acid. 

30. Such are the decomposing powers of electricity, that not cvca 
insoluble compounds are capable of resisting their energy ; for eren 
glass, sulphate of baryta, fluor spar, &c. when moistened and placed 
in contact with electrified surfaces from the Voltaic apparatus, are 
slowly acted upon, and the alkaline, eartliy, or acid matter carried to 
the poles in the common order. Not even the most solid ag^g^g^ErtieSi 
nor the firmest compounds, are capable of resisting this mode of 
attack ; its operation is slow, but the results are certain ; and sooner 
or later, by means of it, bodies are resolved into simpler forms of 
matter. 

31. It is in consequence of the phenomena of electrical decam" 
position, in which metals, inflammable bodies, alkalies, earths, and 
oxides, are determined to the negative surface, and oxygene, chkh 
rine, and acids to the positive surface, that for some time it was con- 
ceived, that various substances might be composed from pure water, 
by means of electricity, such as potassa, soda, and muriatic acid. A 
strict investigation of the circumstances under which these substances 
appeared, led me to discover that they were always furnished fiom 
the vessels, or from impurities in the water, and enabled me to de- 
termine the general principles of electrical decompo^tion, and to 
apply this power to the resolution of some species of matter, of im- 
kno^vn nature, into their elements. 

32. The connection of electrical phenomena and chemical changes 
is evident likewise in the general phxpomena of the battery. The 
most powerful Voltaic combinations are formed by substances that 

• Plate IV. fig. 20. 



[ 91 ] 

act chemically \7ith most energy upon each other ; and such 8ub< 
stances as undergo no chemical changes in the combination, exhibit 
no electrical powers. Thus unc, copper, and nitric acid form a 
powerful battery ; whilst silver, gold, and water, which do not act 
chemically on each other, in series of the same number, produce no 
sensible effect. These circumstances led some philosophers to sup- 
pose, at an early period of the investigation of the electrical powers 
of metals, that they were entirely the result of chemical changes : 
that as heat was produced by this action, when exerted under com- 
mon circumstances, so electncity resulted from it imder other cir- 
cumstances; and many of the phenomena were conformable to such 
an idea, and some ingenious enquirers adopted it to such an extent, 
as to suppose electricity in all cases owing to this cause. 

Tliis generalization, whether applied to Voltaic or to common 
electricity, seems, however, to be incorrect. Zinc and copper, as 
has been stated, different metals and oxalic acid, different metals and 
sulphur, or charcoal, exhibit electrical effects after mere contact, and 
tliat in cases when not the slightest chemical change can be observed ; 
and if in these experiments chemical phenomena arc produced by 
the action of menstrua, all electrical effects immediately cease : and 
it is not philosophical to assume a cause to account for an effect, 
when no such cause can be perceived. 

It has been supposed that the action of the common electrical 
machine depends upon the oxidation of the amalgam ; but I found by 
mounting a small machine in a glass vessel, in such a manner that 
it could be made to revolve in any species of gas, that it was active 
in hydrogene gas, and more active in carbonic acid gas than in the 
atmosphere (probably owing to its greater density). The experi- 
ment has been several times repeated under different circumstances, 
and Uniformly with the same results; and may be regarded as deci- 
sive in this important question. 

33. Electrical effects are exhibited by the same bodies, when act- 
ing as masses, which produce chemical phsenomena when acting by 
their particles ; it is not therefore improbable, that the primary cause 
of both may be the same, and that the same arrangements of matter, 
or the same attractive powers, which place bodies in the relations 
of positive and negative, /. e, which render them attractive of each 



C 92 3 

Other electrically, and capable of communicating attractive powers 
to other matter, may likewise render their particles attractive, 
and enable them to combine, when they have full freedom of 
motion. 

It is not a little in favour of this hypothesis, that heat, and some- 
times heat and light, result from the exertion of both electrical aM 
chemical attractive powers ; and that by rendering bodies, which . 
on contact are in the relation of positive to others, still more highly 
positive, as has been stated, page 89, their powers of combination 
are increased ; whereas, when they are placed in a state correspond- 
ing to the negative electrical state, their powers of union are destroy- 
ed. That acids can be detached from alkalies, oxygene and chlorine 
from inflammable matter by metallic substances, or by a fluid men- 
struum highly positive, is likewise favourable to the supposition. 

34. This view of the possibility of the dependance of electrical and 
chemical action upon the same cause, has been much misrepresented* 
It has been supposed that the idea was entertained, that chemical « 
changes were occasioned by electrical changes ; than which nothing 
is further from the hypothesis, which I have ventured to advance. 
They are conceived, on the contrary, to be distinct phsenomena ; but 
produced by the same fiower^ acting in one case on masses, in the, 
otlier case on particles. The hypothesis has been attempted to be 
controverted by experiments which are far from satisfactory, and 
some of which have no connection with it. It has been said that 
acids rendered positive by the common machine, will still combine 
with alkalies, and that other contradictory xesults may be obtained ; 
but a nonconducting acid, tliough brought in contact witli a positive 
surface, electriiied by the common machine, is not rendered positive 
throughout ; but gains a polar electricity, which extends only to a 
certain depth into the crystals, and the. exterior surface, if electrical 
at all, is negative : and if a wire, positively electrified by the com- 
mon machine, be introduced into an acid solution, this solution, if at 
all aflected, when made to act upon another solution, will be negative 
at its point of action ; that is, it will be positive near the wire, but will 
be in the opposite state with regard to another surface. And com- 
■mon electricity is too small in quantity, in its usual form of applica- 
lioHj to influence chemical changes; for it requires a very strong 



[ 93 ] 

machine acung upon a very small surface, to produce any sensible 
polar decompositions of bodies. 

35. The power of action of the Voltaic apparatus, seems to de- 
pend upon causes similar to those which produce the accumula- 
tion in the Leyden battery, namely, the property of nonconductors 
and imperfect conductors to receive electrical polarities from, and to 
communicate them to conductors; but its permanent action is con- 
nected with the decomposition of the chemical menstrua between 
the plates. Each plate of zinc is made positive, and each plate of 
'copper negative, by contact; and all the plates are so arranged with 
respect to each other as to have their electricities exalted by induc- 
tion, so that every single polar arrangement, heightens the electricity 
of every other polar arrangement ; and the accumulation of power in- 
creases with the number of the series. When the battery is con- 
nected in a circle, the effects are demonstrated by its constant exhi- 
bition of chemical agencies, and the powers exist as long as there is 
;any menstruum to decompose : but when it is insulated, and the ex- 
•treme poles of zinc and copper are unconnected, no effects whatever 
are perceived to take place, no chemical changes go on, and it exhi- 
bits its influence only by communicating very weak charges to the 
electrometer, the end terminated by zinc communicating a positive 
charge, that terminated by copper, a negative charge. 

That each plate of the most oxidable metal in the apparatus, is in 
the relation of positive, and each plate of the least oxidable, in the 
relation of negative, and that every series is possessed of similar and 
equal polarity, is shewn by a very simple experiment : forty rods of 
. zinc of the same size, connected with forty silver wires precisely 
similar, were introduced in the regular order into similar glasses 
filled with a solution of muriate of ammonia, rendered slightly acid 
by muriatic acid ; as long as the extreme parts remained unconnect- 
. ed, no gas was disengaged from the silver, and the zinc was scarcely 
acted upon ; when they were connected, all the plates of zinc were 
dissolved much more rapidly, and hydrogene gas was evolved from 
every silver wire. And in another experiment, in which several of 
these wires at equal distances were introduced into small glass tubes, 
it was found that equal quantities of hydrogene were produced. 




[ 94 ] 

o6. It seems absolutely necessary for the exhibition of the powers of 
the Voltaic apparatus, that the fluid between the plates should be sm- 
ceptible of chemical change, which appears to be connected ^th tbe 
property of double polarity, of being rendered positive at one surfiicCf 
and negative at the other. There are substances that are imperfect 
conductors, which arc capable of receiving only one kind of electri- 
city, when made parts of the Voltaic circuit, and which M. EhrmaOi 
who discovered them, has named unipolar bodies. Perfectly diy 
soap, and the flame of phosphorus, when connected with the two ex- 
tremities of the Voltaic apparatus, and with the ground, discharge 
only the negative electricity. The flames of alcohol, hydrogeae^ 
wax, and oil, discharge under like circumstances only the positife 
electricity ; but all these bodies when connected with one pole oeljr 
of the pile, and with the ground, destroy the divergence of the leaTCi 
of the electrometer connected with that end. It is not difficult to 
exhibit these phxnomena when the atmosphere is dry, by mems d 
two hundred pair of plates carefully insulated: an insulated gjM 
leaf electrometer having a moveable wire attached to it^ a 
connected witli each end of tlie pile : when either electro: 
brought in contact with soap, the soap being connected witK 
ground, the slight divergence of the leaves will cease ; when 
soap is connected with both electrometers and with the g^rouD^ 
divergence of the leaves of tlie electrometer connected with the 
terminated by the zinc, will continue, the leaves of the other electro- 
meter will collapse. The opposite eflect occurs when the flame of 
a taper is connected with both electrometers and with the ground. 

I'he unipolar conductors are incapable of being active in anyiait 
of the pile, and in this respect agree with nonconductors ; mBSjiBt 
which, it is probable, if examined in their relations to electricities 
of low intensity, would exhibit similar diflerences. 

57. There are no fluids known, except such as contain water) 
which arc capable of being made the medium of connection between 
the metals, or metal of the Voltaic apparatus ; and in cases in which 
\'oltaic Ijattcries have been said to be contructed by metals and 
paper, or metals and starch, or other like substances, the feeble 
c fleets produced, are merely owing to the small quantity of water 

icring to these substances, which will not act when carefully 




[ 95 ] 

dried. The instrument, called by M. de Luc, the electrical column, 
formed of zinc, Dutch leaf, and paper, and which he appears to con- 
sider as a different combination from the pile of Volta, seems to be 
merely a feeble Voltaic apparatus, in which the quantity of electri- 
city is not sufficiently great to produce any chemical changes, or 
distinct phaenomena of ignition; but in which the intensity of the 
small quantity existing, when the combination amounts to 400 or 500, 
is sufficient to enable it to affect the electrometer, and to act through 
a plate of air. 

It is very probable that the power of water to receive double po- 

..larities, and to evolve oxygcne and hydrogenc, is necessary to the 
constant operation of the connected apparatus ; and that acids, or sa- 
line bodies, increase the action, by affording elements which possess 
/opposite electricities to each other, when mutually excited; the ac- 
. tion of the chemical menstrua exposes continually new surfaces of 
metal ; and the electrical equilibrium may be conceived in conse- 
quence, to be alternately destroyed and restored, the changes taking 

- "place in imperceptible portions of time. 

The manner in which aqueous fluids receive and communicate 

^■■'electrical polarity, is shewn by a very simple experiment: let a num- 

^.^ber of fine metallic surfaces or flattened wires (of tin for instance) be 
inade to swim in a narrow trough containing water; and let two wires 
from the extremities of a Voltaic battery of 1000 double plates, be 
plunged into the remote ends of the trough, one into one end, the 
other into the other end. The metals swimming on the water will 
imme^atcly acquire electrical polarity ; and the positive and nega- 
tive pbles will be regularly opposed to each other, the pole of the 

w 

metal opposite to the wire positively electrified, will be found to be 
negative, giving off hydrogene, the other pole will deposite oxide ; 
the next wire to this will present the alternate order, which will be 
preserved in all of them ; those most remote from the right line of 
the circuit, will be least affected. If the battery be in a highly active 
state, the different wires will attract each other by their opposite 
poles, and the circle will at length be closed with the production of 
brilliant sparks. The phsenomena are precisely analogous to those 
phaenomena in maghetismy presented by a number of flattened wires 
of soft iron, made to swim upon water, and rendered magnetic by 



[ 96 J 

the opposite poles of two powerful magnets ; each wire has a north 
pole and a south pole; and in the alternation, the different poles are 
attractive of each other. 

38. That the decomposition of the chemical agents is connected 
with the energies of the pile, is eWdent from all the experiments 
that have been made; as yet no sound objection has been urged 
against the theory that the contact of the metals destroys the elec- 
trical equilibrium, and that the chemical changes restore it ; and in 
consequence that the action exists as long as the decompositiou 
continue; and this conclusion is confirmed by the late Tesearches 
made by M. M. Gay Lussac and Thenard, on the great pile coin 
structed by order of the French government. The manner id 
which chemical changes tend to restore the electrical equilibrium, is 
shewn by a remarkable experiment on the electrization of mercurfr 
which I have very lately made. A few globules of mercury are 
placed in a vessel containing common pump water; or any water 
that contains a small quantity of saline impregnation ; wires from 
a battery of 1000 double plates, not very strongly charged, are 
introduced into the vessel opposite to each other, so as to reach 
the bottom; as soon as the circle is completed, the mercury will 
be violently agitated, each globule will become elongated towvdi 
the positive pole, but will retain its circular outline in the part 
opposite to the negative pole; oxide will be given oiT from this parti 
which is positive, but no hydrogene from the part which is negative, 
and the oxide will pass in a rapid current from the positive towaidi 
the negative pole. As long as no hydrogene is given off, the 
globule is in continued agitation, and a stream of oxide flows with 
great rapidity from the positive to the negative sur&ces; and the 
negative sur&ces of the mercury approach rapidly towards the 
positive, which are at rest; if the conducting power of the water is 
exalted by the addition of more of the saline impregnation, or if the 
charge of the battery be increased, hydrogene will be given off from 
the negative poles ; and the instant this happens the globules be- 
come stationary; as if the same power which g^ve motion to the 
mercury was neutralized by, or employed in, the evolution of the 
hydrogene. There are many other remarkable phenomena con- 
nected with the operation of electricity on mercury, in contact with 



[ 97 ] 

water; which may be urged in favour of the idea, that chemical and 
electrical attraction depend upon the same cause, and which will 
possibly lead to new views respecting the elements of matter; but 
the consideration of them properly belongs to a more advanced 
division of this work. 

39. The illustrious inventor of the new electrical apparatus, has 
given it the name of the electromotive apparatus, and has founded 
his theory of its operation upon the Franklinian idea of an electri- 
cal fluid, for which certain bodies have stronger attractions than 
others: and he conceives, that in his pile the upper plate of anc 
attracts electricity from the copper, the copper from the water, the 
water again from the next plate of zinc, the next plate of zinc from 
the next plate of copper, and so on. 

This hypothesis applies very happily to most of the phenomena 
of the action of the insulated pile, and the pile connected by either 
of its extremities with the ground ; but does not explain with the 
same facility, the powers of the apparatus connected in a circle, in 
which each plate of zinc must be supposed to have the same 
quantity of electricity as each plate of copper; for it can only re- 
ceive as much as the copper can give, unless indeed the phxno- 
mena of the circular apparatus be considered as depending upon the 
constant and rapid circulation of the natural quantity of electricity, 
in the different series ; which requires the proof of a constant power 
to attract electricity from one body, at the same time that it is 
giving it off to another. 

40, Whatever may be the happiest approximation to the true 
theory of the Voltaic instrument, it can scarcely be doubted that the 
electrical organs of certain animals depend upon similar arrange- 
ments of exciting bodies. The shock of the Gymnotua Electricusy 
and the Tor/iedoj resemble the Voltaic shock; and the power 
resides in organs which consist of a number of similar alternations 
of different substances. The effects are analogous to those which 
a Voltaic apparatus of small surface, consisting of very numerous 
but not very powerful series, would produce. It has been conceived 
that other phaenomena of living action may be connected with the 
operation of weak electrical powers; such as secretion; and some 
ingenious hints on this subject have been advanced by Dr. Wollas- 

N 



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Z-.-t :'-:zL:t- iri :: ^:. :-, :. :y -_■.-= j.:-:" :: t t^i cjcivirsj. powers: 

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'X-p.o^-c.t: u.:: :..^ ni-.-i: ir=:.=;L=i if ihr e le -=:::* in the earfu 
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4.. ^Vl- :ev^:i *: tl.- ^r^-: ^^^ruljuiTe cui=^::-i- vrheiher the 
^>; -::-/;:: tl-X-V-r.-.r..- dc'c.-.i -:.c-.. cT.c £_:!. L- cxcris in :he bodies 
y.ii.'l.':,'/ tit:--::. jd. u.l ::: dc£::.rz:y Lz. :r-t .Cslies rjeganTcb 
tl^ -•.;.:- tc. or uv-r. *." - i:JT.-:t~: £_;is. r.p^'jrle rvi^eir ccmfaination 
c: j-rviu'ir.;; :.Cst: --'- J^-. :. c: vil,r:..tr il.tv n:^y be paiticuhr 
tz':rjr,:,'. 'ji -«: vjr.tiil i:-.n:u-.± p.vcrsLi n-.i::er. i: is perbaps 
lr..,o ■,.'.„': Vj 'j'.i'l- :r. -.jje %.^ie:.*. :~^:::-t: a:«:e of our know- 
kl;.%. i :.'; i/j-.iciuo:. c: e.= ::::;iy ;•- in ir.5::un:ent of chemical 
<t J.:-. y.'\ .',:.• i:.-: ih-: ^::.Ly of its c£\;c:i, r:^y be carried on inde- 
yr.-.*:.,\ '.f i-.y :.yv:v.tu^i: ideis c:i::-cr-i::;; ii:e origin of the 
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it is composed of severu ccbtr trr^-zi^tis:^ . ■>-." :: i> imross^'iik im 
sound philosophy lo idcpc 5-l-:>. htfcr r'.zstr. '"-.rijarrs: Fnriis. 
Cavendish, £pinus« and Vclu- :ie iL-«r:T'j:i_? ifC"r:i:;L:^i f.-: i:.* 3o«a 
of a single fleet rical £uid- hi»e iC"i-ii.':*_ _; :*:.> li :-77iai:^fi-CiI. ia. 
accounting in a happy way Scr n.-cs: if "Li-t ri-ziii— ;!«.; ii-i zijoit 
of tlie facts that have been brif'-^i: 5: r»Lr-£ la ftrc^jr c-f :^< £c:ukl 
existence either of oce or of fsro fLids*. c,:>i. :•? c^za^Ttd sa cca>- 
clusive. 

From a very ingen!-oi:s cxper'rr.er.t of >5r. C uihbe iisoo- ii appears 
that when a stream of elcc::i:2l s-parts is pas&t:d ir.rouar-: xhe fi^xDC 
of a candle between two tiectriScJ 'urfjces, tl'^e snr£«ce which is 
negative is most heated ; and it has been ar^ed i:^t a currem must 
pass from the positive siuface lo the nc'-^Ive. 

But it is more probable, tliat this phxixinieDon cepends upon the 
positive unijiolar quality of the fiamc of msix or l^low referred to 
above ; for supposing this flame to liecomc positive* which wouid 
seem to be the case, it must be attracted by tlie negative, and not by 
tlie positive surface ; and this view is confirmed by an experiment I 
made on an arch of flame between the tuo poles of the great Voltiuc 
apparatus of 2000 plates. Platuia melted with more facility in the 
arch at the positive than at the negative extremity, and this arch was 
common air intensely ignited, through which the electricity was dis- 
charged ; and if any mechanical current existed from the positive 
pole to the negative, tlie maximum of heat must have been produ- 
ced at the negative. When a wire of platina was made positive, -^^nd 
brought in contact with charcoal rendered negative, it became ignit- 
ed much sooner, and fused into larger gioi^ulcs, than when made 
negative, and brought in contact with the charcoal reijdered positive ; 
and that the effect did not depend upon the greater ucat of the char- 
coal, appears, from the circumstance, ti^at similar pbaenomena oc- 
curred when the experiment was made by contract with mercur}'. 
But when an imperfectly conducting fluid, such as sulphuric acid, 
was used, the result was reversed. The wire being negatively elec- 
trified, and the acid positively, the point in contact i*ith the surface 
of the acid instantly became white hot ; in the opposite case a spark 
of blue light only was produced. 



il-yi 






[ 100 ] 

The different appearance of the light on points positively and n«- 
gatively electrified, has been urged in £avour of the idea of a fluid 
proceeding from the positive to the negative surface. This phasno- 
Hienon occurs as well in the Voltaic, as in the common discharge : 
for when the arch of flame passes between two points of charcoal, a 
vivid spot of white light is always perceived on the negative point, 
smd rays seem to diverge from the positive point The effect of the 
difference of the appearance of differently electrified points, I fiiid» 
does not depend upon the nature of the elastic medium, for it takes 
place in hydrogene, carbonic acid, and chlorine, though it is less dis- 
tinct in the heavier g^sses, probably from their being worse con* 
ductors; but the affections of light in passing from the different 
parts of the circuit, can with no more propriety be urged in Bstvour 
of a specific fluid, than the chemical changes produced by the diffe* 
rent poles. 

When folds of paper are perforated by a discharge from an ele(> 
trical jar, there is a burr on both sides, which may be urg^ as an 
argument against any fluid passing through, for it could penetrate 
in one direction only ; and the experiment is favourable to the idea 
that electricity is an exhibition of attractive powers acting in peco- 
liar combinations ; for the substance of the paper which was nega- 
tive, may be conceived violently attracted to the positive surfu^e, and 
the part which was positive, to the negative, at the moment the dis- 
charge takes place. 

It will be useless to pursue any further this recondite part of the 
subject ; whatever view is taken, active powers must be supposed to 
be bestowed up(Hi some species of matter, and the impulse must be 
ultimately derived from the same source. In the universe^ nothii^ 
can be said to be automatic, as nothing can be said to be without de- 
sign. An imperfect parallel may be found in human inventions ; 
springs may move springs, and wheels, indexes ; but the motkm and 
the regulation must be derived from the artist ; sounds may be pro- 
duced by undulations in the air, undulations of the air by vibratkms 
of musical strings ; but the impulse and the melody must arise from 
the master. 




C 101 ] 

VIII. On Analysis and Synthesis ; on the Circumstances to be attend'^ 
ed to in these Ofierationsj and on the Arrangement of undecom- 
fiounded Bodies, 

1. When a substance is capable of being resolved into other forms 
of matter, it is said to be compounded ^rfj^ll, if mild magnesia (sub-^ 
carbonate of magnesia) be strongly heated for an hour in a green 
glass retort, having its beak connected with a flaccid bladder, elastic 
matter will collect in the bladder ; and the magnesia, when examin- 
ed, will be found to have lost in weight, and to be altered in its pro- 
perties; it will not effervesce with acids, and it is harsher to the feel. 
The weight of the elastic matter collected in the bladder is exactly 
^qual to that lost by the magnesia ; it cannot by any means be con- 
verted into magnesia, and the mild magnesia gives only a limited 
quantity of it ; so it is evident that mild magnesia consists of a mat- 
ter which can be rendered permanently gaseous, and a fixed sub- 
Stance ; it is a comfiounded body. 

The metal called zinc, if heated strongly in close vessels, rises in 
the elastic form, but when condensed by cold, it appears unaltered 
in its properties. It may be distilled any immber of times, but it 
will be stUl the same : nothing permanently elastic, will be given off 
from it ; and if the operations be conducted with care, it will be 
found undiminished in weight. Not even the intense heat of the 
Voltaic battery applied in a vessel exhausted of air, effects any 
change in it ; it easily enters into new combinations, but can be re- 
solved into no otlier forms of matter ; it is considered as an unde^ 
comfiounded body. 

The term element ' is used as synonymous with undecomftounded 
body; but in modem chemistry its application is limited to the re- 
sults of experiments. T^ improvements taking place in the me- 
thods of examining bodies, are constantly chaneing the opinions of 
chemists with respect to their nature, and there is no reason to sup- 
pose that any real indestructible fmncifile has been yet discovered. 
Matter may ultimately be found to be the same in essence, differing 
only in the arrangement of its particles ; or two or three simfile sub- 
stances may produce all the varieties of compound bodies. The 



C 102 ] 

i*esults of our operations must be considered as offering at best ap- 
proximsitions only to tiie true knowledge of things, and should ne- 
ver be exalted as a standard to estimate the resources of nature. 

2. By analysis compounded bodies are resolved into their consti- 
tuents; by synthesis they are produced in consequence of the union 
of these constituents ; an4 when tlie weight of the compound cor- 
responds to that of the cm)4lbents, the processes are considered as 
accurate. 

The words analysis and synthesis are applied in cases when bo- 
dies are resolved into, or compounded from, any other forms of mat- 
ter, without relation to the elementaiy nature of these forms ; — thus 
crystals of Glauber's salt may be resolved anal3rtically into sulphate 
of soda and water, or compounded synthetically from these substan- 
ces ; and sulphate of soda may be formed by synthesis from sulphu- 
ric acid and soda, both of which are compounded bodies. 

3. In all conclusions upon the results of analytical and synthetical 
experiments, it is of the greatest importance that the agencies of all 
the substances concerned, should be accurately known, that no cir- 
cumstance should be taken for granted, and that the nature of the 
real constituents of the body should be shewn to be unchanged dur- 
ing the process. 

Whatever instruments of experiments be used, their relations to 
the substances acted upon should be well known, and their influence 
(if any) estimated. Thus, if a hard stone be pulverized in a mortar 
of porcelain, agate, or iron, the comparison of weights before and 
after the process, should be carefully made, to ascertain what quan- 
tity of matter may have been abraded from the mortar. When 
substances are fused, or heated, in vessels on which they are capable 
of acting, the same precautions should be taken. It should either 
be shewn, that the vessel has been unchanged during the operation, 
or the nature and extent of the change should be demonstrated. 

Many celebrated jhemists have been led into error in the infancy 
of their investigations, from a v/ant of attention to these circumstan- 
ces. Thus the illustrious Scheele for some time supposed that sili- 
cious earth was composed of fluoric acid and water, because he ob- 
tained it by mixing together an acid ^as (procured from fluor spar) 
and water ; but subsequent experiments, by demonstrating the loss 



C 103 ] 

of weight of the glass vessels, in which his operations were con- 
ducted, shewed that the silicious earth was derived from these ves- 
sels, and dissolved in the gas. 

4. Water is the great solvent employed in chemical processes, 
and its operation, therefoi^e, should be strictly attended to. It has 
been too much the custom to consider its elements as almost passive 
in the processes of dissolution and decomposition; but there are a 
number of instances in which these elements are newly arranged, 
and in which their transfer and changes produce very important 
phaenomena. 

When oxymuriatic or chlorine gas is exposed to light, it under- 
goes no change ; but when a solution of it in water is placed under 
the same circumstances, oxygene gas is given off, and a solution of 
muriatic acid is found in the water. Hence it was concluded, with- 
out any reference to weights, that oxymuriatic gas consists of muri* 
atic acid gas and oxygene, and that the water acted in no other way 
than in assisting the expulsion of the oxygene, by its attraction for 
the muriatic acid gas. 

This inference, however, is now known to be incorrect, and it 
affords a striking instance of the present object of discussion. If 
aqueous vapour in small quantities, and chlorine gas, be passed 
through an ignited tube of glass, the steam entirely disappears, and 
oxygene gas, and muriatic acid gas are formed ; therefore the water 
must have entered into the composition of the muriatic acid gas, or 
must have been decomposed; its hydrogene combined with the 
chlorine, to form muriatic acid gas, and the oxygene gas set free ; 
- and that hydrogene actually enters into the composition of muriatic 
acid gas, is proved by the experiment detailed in page 62 ; nor can 
oxygene gas be procured in any experiments upon chlorine, in which 
bodies not known to contain oxygene, alone are concerned ; nor have 
any means been found by which this substance can be decompounded. 

To give another example : when concentrated oil of vitriol, which 
consists of sulphuric acid and water, is poured upon common salt, 
and they are heated together, muriatic acid gas flies off, and sulphate 
of soda is obtained ; hence it was concluded, that common salt con- 
sists of muriatic acid gas and soda ; and that the sulphuric acid 
merely displaced the muriatic acid gas ; and no account was taken 




[ 104 ] 

of the water of the sulphuric acid in the operation ; yet the wliofe 
change depends upon this water, and no soda and no muriatic add 
can be procured from common salt without water ; and commoD Bih 
is made directly by heating sodium, the metal which I discovered 
to be the basis of soda, and chlorine together, and these are both li 
yet undecompounded bodies; and if 92 parts of oil of vitriol, wWck 
consists of 75 parts, by weight, of sulphuric acid, and 17 parts of 
water, be made to act upon 1 1 1 parts of common salt, which consiib 
of 44 sodium, and 67 chlorine, the water will be decomposed, 15 of 
oxygene will combine with the sodium to form 59 of soda, and 3 rf 
hydrogene will combine with 67 of chlorine to form 69 of muriiuc . 
acid gas, and the sulphate of soda will be 134 parts. 

5. There are numbers of substances which possess an attractin 
of a peculiar kind for water ; they absorb water without undergoing 
any remarkable change in their properties, and in small propoitioni 
Such are charcoal, different earths, and animal and vegetable siib* 
stances. If well-burnt charcoal be exposed to the atmosphere fior 
some days, it will increase in weight from 10 to 14 grains per cent^ 
and the increase is almost entirely owmg to its absorbing water, wUch 
existed in the form of vapour in the air ; and by heating charcod 
that has been exposed to air, in close vessels, the water may be 
collected unaltered. Baryta, strontia, and lime, absorb defimte pro- 
portions of water, and form what are called hydrates, in which the 
water is in chemical combination, and requires an intense heat fe 
its expulsion ; and magnesia, alumina, silica, glucina, and zircooii 
likewise increase in weight by attracting aqueous vapour from the 
atmosphere, and seem to form analogous combinations ; they give 
off all the water they had absorbed at the temperature of dull igni- 
tion, so that it is retained in them by a very weak attraction ; and 
that the water absorbed in this way is in true chemical union with 
the earths, is still farther proved by the circumstance that a hydratt 
of one of these bodies exists in nature, namely, the wavellite or hy- 
drate of alunune, and this is a crystallized body, and requires a 
strong red heat for the expulsion of its water. 

Compounds of tlie earths in fine powder, that have been heated 
red, increase in wei,u^ht, from the absorption of atmospheric moisture; 
nd the case is the same with almost all substances, except the me- 



[ 105 ] 

tals, and certain inflammable bodies : so that, in all experiments of 
analysis, the solid products obtained should be strongly heated, and 
weighed whilst warm, and before they have been long exposed to 
the atmosphere, or the quantity of water tlicy have absorbed should 
be exactly known. And the same precautions should be used, and 
more strictly, with respect to alkaline, acid, and saline bodies that 
enter into chemical combination witli water, and attract it rapidly 
from the atmosphere. 

6. Gaseous bodies arc usually procured from substances that con- 
tain water, and many of them are collected over water ; it is tlicra* 
fore of considerable importance, in analytical processes, that their 
relations to this substance should be distinctly understood. 

It has been already stated, that common air contains aqueous va- 
pour, or water in an invisible clastic form, which is greater in pro- 
portion as the temperature is high, air at the temperature of 65° 
Fahrenheit, containmg about -^ of its volume. From the experi- 
ments of Desormes and Clement, it appears that all the gasses not 
absorbable to any extent by water, such as oxygenc, azote, carbonic 
acid, and hydrogene gasses, contain, in equal volumes, the same 
quantity of vapour as common air ; so that vapour, when it exists 
in these bodies, can only be regarded as mixed with them ; and it is 
separated by substances that have a strong chemical attraction for 
water, such as lime, muriate of lime, sulphuric acid, hydrate of po- 
tassa, 8cc. ; and in all accurate experiments in which gasses are exa- 
mined, they should be previously freed from vapour by exposui'c fur 
some hours to substances that have a strong attraction fur water, but 
possessed of no chemical action on the gas. 

The relations of water to gasses with wliich it is capable of com- 
bining chemically (which gasses will be described hereafter), are 
Tcry different. It is evident that no pure aqueous vapour can exist 
in them in a state of mixture^ but they may, and probably in almost 
all cases do contain a gaseous compound of water, and tlie peculiar 
elastic fluid. If a drop of water be introduced into a flask filled 
with ammoniacal gas, it rapidly absorbs the gas, and increases in 
size ; but if a minute drop of a concentrated solution of ammonia be 
introduced, and the temperature of the flask be gently raised, the 
drop disappears, and continues invisible^ as long as the heat is prc- 

o 



C 106 ] 

sen-ed uniform. The instances are similar when analogous experi- 
ments are made upon 'muriatic acid andsilicated fluoric acid gasses; 
and I have found that these elastic fluids collected at the temperature 
of 75° deposited a slight dew, consisting of strong solution of add 
in water, when intensely cooled by a freezing mixture. There ii 
reason to believe that the case must be the same with Huoboric acidi 
and that this body may contain a minute quantity of the compound 
which may be called hydrate of fluoboric acid ; and this is confirmed 
by the phaenomena of the action of potassium upon the gas, for I 
have never been able to decompose it by this substance^ without 
procuring small quantities of hydrogene. 

The quantity of water in tlie gasses for which it has a chemical 
attraction, must depend upon the degree of volatility of the fluid 
compound of the gas and water, and upon tlie proportion rf 
■water it contains. Sulpliureous acid gas, which has only a weak 
atti'action for water, would, there is every reason to believe, cuntun 
most of the gaseous hydrate ; but even in tliis it is most likely theit 
must be less water than in common air at the same temperature; 
ammonia would probably be next in order, tlien silicated fluoric gaa, 
muriatic acid gas, nitrous acid gas, and, last of all, fluoboric gas. 

The temperatures at which the compounds of water and gassM 
rise in vapour, seem to depend upon the strength of the attractiorij 
by which they are combined, and upon the degree of volatility of the 
gaseous element. All solutions of sulphureous acid, and ^unmonU) 
boil at temperatures which differ veiy little from the boiling point of 
water. The highest point of the ebullition of solution of muriatic 
acid gas in water is about 232<> Fahrenheit; that solution of nitric 
acid which gives a compound vapour, does not boil at a tempera- 
ture below 248" ; the temperature at which hydrated fluoric acid 
boils, according to M. M. Gay Lussac and Thenard, is not very high; 
but the vapour contains a considerable quantity of water, compared ) 
with other acid vapours. 

Whether substances will attract water from the absorbable gasses, 
must depend upon the strength of their affinity for water, as com- 
pared with that of the gas. Dry hydrate of potassa will slowly attract 
moisture from ammonia, and dry muriate of lime from sulphureous 
acid gas; but muriate of limo does not appear to act upon the water 




C 107 ] 

in muriatic acid gas. Silicated fluoric acid gas and fluoboric gas, 
instantly render cloudy sulphureous acid gas by attracting moisture 
from it, and fluoboric gas, if mixed with fluoric acid gas, renders it 
very slightly cloudy. Probably there arc no substances which will 
attract water from the vapour of hydrated fluoboric acid ; but the 
quantity is too minute to influence, to any extent, the results of ex- 
periments on gasses containing it. 

In cases when elastic fluids arc produced in contact with sub- 
stances which aflbrd peculiar vapours, such as volatile oils, alcohol, 
ether, Sec. ; these vapours should be separated either by agitating the 
gasses in water, or solutions of substances which arc capable of ab- 
sorbing them, such as solution of potassa, &c. and the aqueous vapour 
separated afterwards by the means alx)ve mentioned. 

7. In stating the weights, of bodies which are the results of analyti- 
cal experhnents, the temperature should be noticed ; and in the case 
oCJlastic fluids, the degree of pressure of the atmosphere, as indi- 
cated by the barometer. When gaseous compounds are resolved 
into simpler gaseous bodies, or when gasses are compared with each 
other, as they are all similarly aflected by heat and pressure, there 
is no necessity for any specific statements of these circumstances^ 
and in describing the specific gravity of a gaseous body, it is neces- 
sary only to give the relation of its weight to that of air ; thus the 
weight of air being 1000, that of oxygene gas will be 1097. As hy- 
drogene gas is much lighter than any other elastic fluid, and as it is 
the body which combines with other substances in tlie smallest pro- 
portions, it would perhaps assist the progress of chemical enquiry 
to denote its specific gravity by unity, which would harmonize with 
the idea of representing the proportion in which it combines like- 
wise by unity, and would facilitate the means of comparing the ab- 
solute weights of gaseous bodies concenied in experiments, with 
the numerical symbols representing their elements. The specific 
gravity of hydrogene being considered as 1, that of common air 
will be 13.7, and that of oxygene, as has been stated in page 
63| 15. 

8. In treating of the different substances which, by their agencies, 
combinations, or decompositions, produce the phsenomena of che- 
jmstry-'^radianf or etheriai matura will be first considered, as their 



[ 108 ] 

principal effects seem rather to depend upon their communicating 
motion to the particles of common matter, or modifying their attrac* 
tionSf than to their actually entering into combination with them; 
and as from the laws of their motions, or from their extreme sub- 
tileness, they are incapable of being weighed. 

The undecomfiounded substances which are permanent in their 
forms, will be considered in an order of arrangement depending 
upon their electrical relations ; those determined to the fioailive sur- 
face in the Voltaic electrical circuit, being arranged in one class, and 
those determined to the negative surface in another ; and the sub- 
divisions of the classes will be made according to their natunJ 
relations. 

The general principle adopted will be, that no compounded body 
shall be treated of, till its constituents have been described. 

■ 

The relations of bodies derived from their electrical powers, ait 
coincident with those dependent upon their agencies in combusti^y. 
that is, one class contsdns supporters of combustion, and the other 
class combustible bodies ; but as the heat and light produced in com- 
bustion, seem to be merely indications of the strength of attraction el 
the acting substances; and as these phenomena occur ih cases in 
which inflammable matters act upon each other, combustibility can 
-scarcely be considered as a definite idea; though the importance of 
the common phaenomena of combustion, have made them the grand 
objects in all the early theories of chemistry. 



[ 109 ] 



DIVISION n. 

OF BADIANT OR ETHEREAL MATTER. 

- 1. Of the effects of radiant Matter .^ in producing the fih^tnomena 

of Vision, 

1« 1 HE phenomena of vision depend upon the presence of the 
SUH) of the heavenly bodies, or on the mutual action of certain sub- 
stances on the surface of the earth. 

2. It has been demonstrated by Roemer, and confirmed by the dis- 
coveries of Bradley, that the motion of light is progressive ; it is 
about eight minutes in passing from the sun to the earth. 

3. When light is endrely intercepted by a body placed betweea 
the luminous object and the eye, that body is said to be opaque ; and 
the manner in which the light is intercepted, proves that it proceeds 
in right lines or rays from the luminous body as a centre. 

4. Luminous objects may be seen through certain substances; 
and these bodies are said to be transparent. Bodies differ considera- 
bly in the degree of their transparency ; some transmit many more 
i*ays than others, and there arc gradations from perfect opacity, 
ivhen all the rays are intercepted, to a high degree of transparency, 
when by far the greater number are transmitted. 

5. Of the rays that are not transmitted, some are lost, as it were 
absorbed by the body ; others are tlirown back again, or reflected 
from its exterior or inner surfaces, and these rays are called re- 
flected rays. 

6. The rays of light, in their transmission through bodies, or re- 
flection from their surfaces, undergo certain modiHcatioQS, of great 
importance in their connection with the laws of vision, and the general 
properties of radiant matter. 



[ no ] 

7. If rays of light pass from one transparent substance not crys- 
tallized into another, in an oblique direction, their path is altered^ 
and they are bent downwards or upwards, according as the medium 
is more or less dense, or according as it differs in chemical quali- 
ties ; inflammable substances, or compounds containing inflammable 
substances, having the highest power of bending towards the per- 
pendicular or of refracting, as it is called, the rays of light ; and, in 
the same substances, the sines of the angles of refraction bear al- 
ways the same relations to those of the angles of incidence. 

8. The rays of light, in passing through obliquangular crystalline 
bodies, follow different laws. If a ray of light be received perpen- 
dicularly upon a plain surface of island crystal, or rhomboidal car- 
l)onate of lime, one part of it passes through without altering its dir 
rcction ; another part, on the contrary, is refracted in a plane parallel 
to the diagonal, joining the two obtuse angles of the crystal, so that 
images seen through the crystal appear double ; and this phaenome- 
non, first scientifically reasoned upon by Huygens, is called the phe- 
nomenon of double refraction. 

If a ray of light which has suffered double refraction from one 
crystal, be received by another cr>*stal placed in a similar and paral- 
lel position, there will be no new division of rays, and no change in 
their direction ; but if the second cr\-stal be placed, so that its planes 
of perpendicular refraction are at right angles to those of the first 
cr)-stal, then there will be a new phaenpmenon, and that part of the 
ray which before passed through the ordinary refraction, will receive 
the extraordinary refraction, and reciprocally that which underwent 
the extraordinary will suffer the ordinary refraction. If the second 
crystal be turned gradually round in the same plane, when it has 
made a quarter of a revolution, there will be four divisions of the ray, 
and they will be reduced to two in the half of the revolution, so that 
the refracting power depends upon the relations of the position of 
the panicles of the crystals, to the rays passing through thexn. 

Similar phenomena to those presented by island crystal, are ex- 
hibited in a greater or less degree by other crystalline bodies, and 
probably would belong to dl of them, if ihey were sufficiently trans- 
I>\;vnt to admit of the passaj^* of li^ht through strata of considerable 




[ 111 ] 

thickness. Very thin pieces of the rhomboidal carbonate of lime 

> even do not give perceptible, double images. 

9. When light is reflected from bodies, under most circumstan- 
ces it is unaltered in its relations to the refractive powers of transpa- 
rent substances, and the angle of reflection is equal to the angle of 
incidence. But, in certain cases, at angles which differ for different 
bodies, the reflected rays have the same property as the extraordi- 
nary refracted rays that have passed through island crystal. This 
important fact, discovered by M, Mahis, is easily exemplified. If 
the flame of a taper reflected at an angle of 52® 45' fi'om the sur- 
fece of water, be viewed through a piece of double refracting spar, 
one of the images will vanish every time that the crystal makes a 

. quarter of a revolution. 

If a ray of light be reflected from a surface of glass, at an angle 
of 54° 35', and fall upon another plane of glass at the same angle, it 
will suffer no new i*cflection, arid will pass through the glass unal- 
tered, provided that the planes of reflection or refraction be perpen- 
dicular to each other ; but if they are in the same direction, nothing 
remarkable will happen. 

Direct light is most copiously reflected, as its incidence is less 
perpendicular ; but light once reflected follows different laws, and 
the quantity that suffers the second reflection, depends entirely upon 
"the relations of the angles made by the reflecting surfaces with the 
rays. 

10. When a ray of light is made to pass through a triangular 
prism of glass, and the transmitted light is received upon a sheet of 
white paper, it is found to be of different colours ; the most distinct 
of which are red, orange, yellow, green, blue, indigo, and violet. 
Newton has ascertained, that if the coloured image, or spectrum, as 
it is called, be divided into 360 parts, the red will occupy 45 of these 
partsj the orange 27, the yellow 48, the green 60, the blue 60, the 
indigo 40, and the violet 80. The red rays are least refi'acted, the 
violet rays most, and the other coloured rays are refrangible inverse- 
ly, in the order in which they have been named. 

According to Dr. Wollaston, when the beam of light is only ^^g- of 
an inch broad, and received by the eye at the distance of ten feet. 




C 112 3 

tbrou^ii a dear prism of fiini ^lasu fo'^r colours ocilr appear, k4 
ytllovish green, blue, and "lioleu 

If llie diiferemly colouxtrd rays of light separated by the prism, be 
concentrated upon one sp>ot by mears of lenses, they produce iriitt 
Cght ; and Newton has beautifully explained the different coloon d 
bodies, by supposing tiiat they retail certain of the coloured nysrf 
light, axid reject others : thus red bodies are supposed to reflect id 
light, and to absorb all the other ccloured rays. 

The differeijt coloured rars of l:ght* as has been shewn by Dr., 
Ilerschel, diner in tr^eir power of rendering objects visible ; at kai 
in the state of division, which is ob'.ained by means of a prism. I 
an equal portion of these rays be made to illuminate a printed pagt^ 
the wordb may be seen fro:n the greatest distance, when exposed tl 
the lightcbt green or deepest yelloa light ; and the effects of illunfr 
nation for equal quantities of the ray s, diminish from the central putt 
towards the extremities of the spccmim. It may, however, be oU 
that tlierc are more green rays in a given part of the spectrum tiai 
blue rays, and tlie difference of illiminating power may depend si^ 
this circumstance. 

) 1 . The rays separated by one prism are not capable of beiD^ 
further divided by l>eing passed through another; and in their rdi' 
tjous to double refraction and reflection, they appear to agree wiA 
direct light : an object illuminated by any of the rays in the spcfr 
trum, is seen double through island crystal, in the same manner tf 
if it ha'i been visible by white light. 

12. l*he minute investigation of the properties of radiant mattO) 
rn their relations to tlie phenomena of vision, constitutes the object 
of a particular branch of science — 0fiu'c9. The few statements thtf 
have been made on this subject, it will be found in the following 
pages, are connected with the chemical effects and nature of radiiflt 
matter ; ai:-d it will immediately be seen, that the same causes which 
produce the most numerous and important of our sensations, nd 
which give, as it were, language to the external world, are likewise 
subservient to the orderly succession of events in the oeconomy of 
nature. 



[ 113 ] 

11. Of the Ojicration of radiant Matter in firoducing Heat, 

1. When similar thermometers arc placed in the different parts 
jof the solar beam, separated by the prism, it is found- that different 
.effects are produced in the different coloured rays. The greatest 
^eat is exhibited in the red rays, the least in the violet rays ; and in a 
space beyond the red rays, where there is no visible light, the in- 
crease of temperature is greatest of all. This important discover)- 
^was made by Dr. Hcrschel*. He estimates the power of heating 
in the red rays, to be to that of the green rays as 55 to 36, and to 
tihat of the violet rays as 55 to 16. A thermometer, in the full red 
xays, indicated an increase of temperature of 7** Fahrenheit in ten mi- 
nutes ; beyond the red rays, in an equal time, the increase was 9*^ 
Fahrenheit. 

■ . 2. From these facts, which have been confirmed by Sir H. Engle- 
j^ld, and other good observers, it is evident that matter set in mo- 
^^n by the sun, has the power of producing heat without light, and 
tlhat its rays are less refrangible than the visible rays. 

Some persons have concluded from the phxnomena, that all the 
mys which produce heat in the solar beam, are distinct from those 
"that produce light ; but this does not seem to be warranted by the 
experiments, for if it were the case, they would, probably, be entire- 
ly separated from the coloured rays by the prism, as the coloured 
Tays are from each other. It has been used as an argument, in fa- 
-vour of the distinctness of the rays producing light, and those pro- 
Tlucing heat, that the beams from the moon illuminate without heat- 
'inTg ; hut it is possible that a greater number of the most heat- 
~ making rays, than of the other rays, may be absorbed by that planet ; 
and supposing all the rays reflected that fall upon the moon, yet still 
iheir intensity would be 95890 times less than that of the solar rays, 
St the surface of the earth : and it appears from experiment, that the 
real intensity of the light of the moon to that of the sun is less than 
1 to 300^0, and such rays concentrated by the most powerful Icn- 
ies> could not be expected to produce any effect on common thermp- 



* Philosophical Transactions, 1800, p. 261, 

p 




C 114 ] 

meters ; and as yet no very delicate experiments have been publish- 
ed on the subject. 

3. The invisible rays that produce heat, are capable of reflection 
as well as refraction, in the same manner as the visible rays. It is 
well known that an intense degree of heat may be produced by the 
concentration of tlie solar beams upon a single spot, by a concave 
mirror, or by several mirrors ; and there is no reason to disbelieve 
the fiosMiliiy of the inventions asciiijed to Archimedes, who, it is 
said, by the combined cftect of a number of plane mirrors, set fire to 
the Roman ships dunng the siege of Syracuse ; tliough the immense 
means and labour required for such an operation, renders the narra- 
tive vciy doubtful. 

4. Rays capable of producing heat with and without light proceed 
from bodies at the surface of the globe under peculiar agencies or 
changes, as well as from the sun ; and the phaenomena that are 
usually called the phenomena of the radiation of terrestrial heat arc 
of great extent and importance, and well worthy of being studied. 

5. If a thermometer be held near an ignited body it receives an 
impression connected with an ele^'ation of temperature : this is paitly 
produced by the conducting powers of the air; but it is likewise pro- 
duced by another impulse which is instantaneously communicated, 
even to a considerable distance. If a large concave metallic mirror 
be placed upon the ground, and the hot body be raised some feet 
above it, a thermometer will instantly rise in the focus of the mir- 
ror, though it is evident that no current of hot air can pass down- 
wards from the body. 

This effect is commonly called the radiation of terrestrial heat. It 
is best observed, by employing two mirrors parallel to each other, 
and to the surface of the earth. If the mirrors be of copper tinned, 
and be well polished, and as much as 2 feet in diameter, and distant 
only 12 feet, a small pan of red hot charcoal, placed in the focus* of 
the upper mirror, will cause gunpowder to explode in the focus of 
the lower miiTor. 

* In the usual form of the experiment, the mirrors are placed opposite to each 
other on the ground. This arrangement, which I have been long in the habit of 
employing, in the demonstrations in the theatre of the Royal Institution, moic 
distinctly exhibits the effect. See Plate IV. fig. 21. 



[ 115 ] 

6. In cases when no light is emitted from a hot body, the effect of 
the concentration of heat by the mirrors may still be produced. 
Thusy if a vessel filled with boiling water, be placed in the focus of 
the upper mirror, a thei*mometer placed in the focus of the lower 
one will have its temperature increased. 

These phenomena of the radiation of terrestrial matter producing 
heat, were made known by the academicians Del Cimento, Hooke, 
Schcele, and Pictet : and there is another fact, still more extraordi- 
nary, which has beeu called the radiation of coidj first observed by 
the Italian philosophers, and afterwards by Pictet. If in the arrange- 
ment of the two parallel mirrors, a piece of ice be introduced into 
tiie lower focus, the thermometer in the upi>er focus will indicate a 
diminution of temperature. 

^. All these phaenomena coincide with the phaenomena of the 're- 
flection of the solar beams; and even the a/i/iarent radiation of cold 
is in harmony with them ; for if it be supposed, that rays capable of 
pi*oducing heat, emanate from all terrestrial bodies, but in quantities 
greater in some increasing proportion as their temperatures are 
higher, then the introduction of a cold body into the focus of one mir- 
tor, ought to diminish the temperature of a thermometer in the fo- 
cus of the other, in the same manner as a black body placed in one 
fi>cus, would diminish the quantity of light in the other focus; and 
the eye is to the rays producing light, a measure, similar to that 
which the thermometer is to rays producing heat. 

8. If a large lens be placed before an ignited body, and the light- 
be refracted to a focus, a thermometer placed in the focus will be 
very slowly affected. The increase of temperature will be infinitely 
less than that produced in the focus of a mirror of the same size, and 
is such as may be principally ascribed to the increased radiation of 
heat by the lens itself. Likewise, if glass screens be placed between 
the two mirrors, in the experiments in which the ignited coals, or 
water, or ice are used, the eftect is in great measure destroyed. 
This establishes a difference between the agency of the radiant mat- 
ter producing heat on the surface of the earth, and of that from the 
sun. Mr. Leslie has supposed that the phenomena of the radiation 
of terrestrial heat, depend upon certain pulsations or undulations of 
tlic atmosphere capable of being reflected, but not of being refract- 




L ii6 J 

ed; but none of his facts prove this ingenious hypothesis, thougb 
many of them are favourable to it. I had an apparatus made, bf 
%?hich platina wire could be licatcd in any elastic medium, or in n- 
cuo ; and by which the effects of radiation could be distinctly 
bited by two mirrors, the heat being excited by a Voltaic bai 
In several experiments, in which the same powers were empi 
to produce the ignition, it was found that the temperature of a tho^ 
mometer rose nearly three umes as much in the focus of radiadoi^ 
when the air in the receiver was exhausted to -j^-^j as when it yru 

■ 

in its natural state of condensation*. The cooling power, by contact , 
of the rarefied air, was much less than that of the air in its commoa ' 
state, for the glow of the platina was more intense in the first caia 
than in the last ; and this circumstance perhaps renders the expeii- 
ment not altogether decisive, but the results seem favourable to tha 
idea, that the terrestrial radiation of heat is not dependent upon $Bf. ' 
motions or affections of the atmosphere. 

9. Another fact coinciding with this opinicHi, is found in the efiett^j^ 
of the refraction of the rays from charcoal, ignited by Voltaic clefr-, 
tricity. When a small lens was placed before the brilliant star oE- 
light, produced by the battery of two thousand double plates, and iti, 
focus thrown upon the ball of a small differential thermometer, the 
instrument instantly indicated an elevation of temperature. 

10. The manner in which the temperatures of bodies are affected 
by rays producing heat, is different for different substances, and is 
very much connected with their colours. The bodies that absorb^ 
as it is called, most light, and of course that reflect least, are most 
heated when exposed either to solar or terrestrial rays. Black bo- 
dies in general are more heated than red; red more than grees; 
green more than yellow ; and yellow more than white. 

Metals are less heated than earthy or stony bodies, or than animal 
or vegetable matters. Polished surfaces are less heated than roug^ 
surfaces. 

11. The bodies that have their temperatures most easily raised by 
the action of rays producing heat are likewise those that are most 
easily cof^lcd ly their own radiation, or that at the same temperature 

» Sec Pliitc IV. llg. 22. 




C 117] 

emit most heat-making rays. Metals radiate less heat than glass; 
glass less than vegetable substances; and charcoal has the highest 
radiating powers of any body as yet made the subject of experiment. 
^^ From Mr. Leslie's ingenious researches, it appears that the radi- 
ig power of lamp-black, being taking as 100, the following sub- 
iCes radiate in a proportion that may be thus expressed : sealing- 
wax 95; crown glass 90; China ink 88; ice 85; minium 80; isin- 
glass 80; plumbago 75; tarnished lead 45; clean lead 19; polished 
iron 15; tin plate, gold, silver, and copper 12. 

12. There are some practical applications of the doctrines of 
radiant heat, to the oeconomy of some of the useful arts and proces- 
ses of common life. 

Vessels that are intended to retain their heat, should be metallic 
and highly polished ; and, independent of elegance and delicacy, 
there is a reason obvious, from the preceding facts, why metallic 
vessels, for the purposes of the table, should be kept as bright as 
possible. Steam or air pipes for wanning houses, should be polish- 
ed in those parts where the heat is not required to be communi- 
cated, and covered with some radiating substance, such as lamp 
black, or plumbago, in those rooms which are to be heated by them. 

Culinary implements should be blackened, and not polished on 
those parts, which are to receive heat. The heated surfaces of fire- 
places or stoves should not be metallic; but of stony or earthy 
materials, and in this case much more heat will be communicated 
by radiation*. 

III. Of the Effect 9 of radiant Matter in jiroducint^ chemical Changes. 

1. A number of the effects of radiant matter in producing chemi- 
cal changes, may be ascribed to its powers of heating bodies. The 
heat produced by the concentration of rays has been already referred 
to, and the focus of a powerful lens or mirror exposed to the sun, 
offers means of exciting heat inferior only to those afforded by 
Voltaic electricity. In some cases the direct solar light produces 
effects similar to those produced by a degree of heat much higher 

* Count Rumford. Phil. Trans. 1804, page 178. 







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•.',f TO •• -!> <f .r! OS -» or-iif-.i v.itTi .loiTi iiiver ^ ^iacitened 3f 

.' .-^'A- . j/*.^: tii^r^ofiip.-: ;a' 'i'.tise .n":sii;ic .nvs i:"s mixed wiCi 

./.o'^ic ,r|.'4!'." y'' >'>'*: *'p.. ."5»r. Ill* *;":;V4»- ."^vi :-"4a: ■sr^iiiice liirht* mar 

v.-.'r' ^.•v'm'^-. -.: »v.'r.''<«; ':Vi!'.-:*- li^r. ta inra •:£ -lear; and Dr" 

'/■.•■' 't .'IK •*»-^ '•'. '■ :»»■ .'f ..■ si.-,i«- "1 "i i."'r -iai;ie "tq "Lie soxne affcc- 
-• 

•If,? '-. I < •".'■.i'.'*" "i-;-^ ' '.«*.r. ■.••'/ "t."^ ."'5*" if:**!! from "iiln plares of air. 

/t ; ■''.'. \.f\ '■ •' « r.-../:.: ^'. "/ ^...:.',rir.e and hydrc^^ene acted more 

f^r,'f^ f .,*-,• ' •" ., «-/ -,#■ •. --y/v. „....-.■; -^ '::.-. v:* txplo-aion. when cxpos- 

", •/, ■,'■ ."'i .M,.4, ^.i;-, v! f;;. i,\'.r,c/\ 'v. ih** v-Iolet rav5 ; but that 

igf^l^yn <,f ' ..'....',' .n viv-r. ,'-. jrrs^; -voluVic^n cf muriatic acid most 

^^■L wh' i» ;.. .'."I 111 M.'; ffiosr rf;fnin:.i!^lc rays in the spectrum. 

'^bwl H,i* *..' ;i'i' "/i'/iii'.'l oy.i''li; of lead, when moistened^ 

Vf $^»ii.f'/i • Mr.? '/) re/} in the Icusi refruii^^ible rays, and at last 



C 119 ] 

l»ecame black, but was not affected in the most refrangible rays ; and 
the same change was produced by exposing it to a current of hydro- 
gene gas. The oxide of mercury procured by solution of potassa 
and calomel, exposed to the spectrum, was not changed in the most 
refrangible rays, but became red in the least refrangible rays, which 
must have depended upon its absorbing oxygene. The violet rays 
produced upon moistened red oxide of mercury, the same effects as 
hydrogene gas. 

6. The general facts of the refraction and effects of the solar 
beam offer an analogy to the agencies of electricity. In the \'oltaic 
circuit the maximum of heat seems to be at the positive pole where 
the power of combining with oxygene is given to bodies, and the 
agency of rendering bodies inflammable is exerted at tlie opposite 
surface; and similar chemical effects are produced by negative 
electricity, and by the most refrangible rays of the solar beam. 

7. In general, in nature, the effects of the solar rays are ver>- 
compounded. Healthy vegetation depends upon the presence of 
the solar beams, or of light, and whilst the heat gives fluidity and 
mobility to the vegetable juices, chemical effects likewise are oc- 
casioned, oxygene is separated from them, and Inflammable com- 
pounds formed. Plants deprived of light become white, and contain 
an excess of saccharine and aqueous particles ; and flowers owe the 
"variety of their hues to the influence of the solar beams. 

Even animals require the presence of the rays of the sun, and 
their colours seem materially to depend upon the chemical influ- 
ence of these rays; a comparison between the polar and tropical 
animals, and between the parts of their bodies exposed, and those 
not exposed, to light, shews the correctness of this opinion. 

IV. Of the Miture of the Motions or Affectiona qf radiant Matter. 

1. Two h)rpotheses have been hiverted to account for the princi- 
pal operations of radiant matter. In the first it is supposed that the 
universe contains a highly rare elastic substance, which when put 
into a state of undulation^ produces those effects on our organs of 
sight, which constitute the sensations of vision, and the other phae- 
nomena occasioned by solar and terrestrial rays. In the second it is 



N 



^ 



C 1203 

conceived that fiarticlc% are emitted or sent off from luminous op 
heat-making bodies with great velocity, and that they produce their 
effects by communicating their motions to substances, or by entering 
into them, and changing their composition. 

2. The first of these suppositions was adopted by Hooke, Huy- 
j^ns, and Euler; — ^the second by Newton, and the philosophers of 
the Newtonian scliool. Many of the phsenomena may be accounted 
for by either hypothesis, but the Newtonian doctrine applies much 
more happily to most of the facts discovered respecting the modifi- 
cations of light by double refraction and reflection. Indeed it does 
not seem possible, as Newton has shewn, to account for the circum- 
stance, that a ray which has suffered extraordinary refraction in 
passing through one crystal, should suffer ordinary refraction in 
passing in another direction, through another like ci^stal, on the 
idea of the effect being a mere undulation of an ethereal medium 7 
but it may explained by supposing the rays to consist of particles 
endowed with rectilineal motion, and possesed of a certain polarity^ 
that is, parts attractive with respect to some surfaces of the crystal, 
and repulsive with respect to others. 

3. M. Malus has supposed, in his ingenious speculations on these 
remarkable phenomena, that the molecules producing light, are 
possessed of three rectangular axes, of which one is always in the 
direction of the ray, and the other two are made by the influence of 
the repulsive forces exerted by the crystalline medium, perpen- 
dicular to the direction of these forces ; and such a form, and such 
an effect would correspond with the idea of the luminous particles 
being octaedrons. 

4. As the coloured rays separated by the prism, bear the same 
relation to double refraction, that direct light bears, it follows that 
the polarity of the different particles must be of the same kind, and 
tills is what might be expected. The same crystalline substance 
ahvays affects the same primary forms. When a tourmaline is 
broken into pieces, the pieces are found to possess similar electrical 
powers to the original crystal, and a large rhomb of calcareous 
spar, easily breaks into a number of small rhombs. 

5. Newton has attempted to explain the different refrangibility of 
ys of light, by supposing them composed of particles differ- 




C 121 3 

ing in slzC} and this hypothesis is not contradictory to the idea of 
their being regular solids endowed with similar polaiities. The 
same great man has put the query whether light and common mat- 
ter are not convertible into each other ; and adopting the idea that 
the phaenomena of sensible heat depend upon vibrations of the par- 
ticles of bodies, supposes that a certain intensity of vibrations may 
send oiT particles into free space, and that particles in rapid motion 
in right lines, in losing their own motion, may communicate a vi- 
bratory motion to the particles of terrestrial bodies*. 

* The views of Newton are so clearly developed in the following passages, and 
^tlley are so much connected with the refined philosophy of chemistry, that the 
leader probably will require no apology for the insertion of them in a note. 

Quere 29. Are not the rays of light very small bodies emitted from shining 
nibstances ? For such bodies will pass through uniform mediums in right lines, 
without bending into the shadow, which is the nature of the rays of light. They 
wHl also be capable of several properties, and be able to conserve their properties 
liachanged, in passing through several mediums, which is another condition of the 
Jays of light. Pellucid substances act upon the rays of light at a distance, in re- 
fiacting, reflecting, and inflecting them ; and the rays mutually agitate the parts 
.of those substances at a distance for heating them ; and this action and re-action 
at a distance, very much resembles an attractive force between bodies. If refrac- 
tion be performed by attraction of the rays, the sines of incidence must be to the 
aiqes of refraction in a given proportion ; as we shewed in our principles of phi- 
losophy, and this rule is true by experience. The rays of light in going out of a 
^as8 into a vacuum, are bent towards the glass ; and if they fall too obliquely on 
the vaettum, they are bent backwards into the glass, and totally reflected ; and 
tills reflection cannot be ascribed to the resistance of an absolute vacuum, but must 
be caused by the power of the glass attracting the rays at their going out of it into 
the vacuum, and bringing them back. For if the farther surface of the glass be 
xnoistened with water, or clear oil, or liquid and clear honey, the rays which 
Tvoqld otherwise be reflected, will go into the water, oil, or honey, and therefore 
axe not rejected before they arrive at the farther surface of the glass, and begin 
to go out of it. But if they go out of it into a vacuum, which has no attraction 
to balatice that of the glass, the attraction of the glass either bends and refracts 
them, or brings them back and reflects them. And this is still more evident by lay- 
ing together two prisms of glass, or two object-glasses of very long telescopes, the 
one plain, the other a little convex, and so compressing them that they do not 
fnlly tciich, nor are too far asunder. For the light, which falls upon the further 
surface of the first glass, where the interval between the glasses is not above the 
ten.bnndred thoiisandth part of an inch, will go throi:;;h that surface, and through 



[ 122 ] 

6. As particles of any gaseous medium when put into a state of 
uiidulatory motion are capable of producing the sensation of sound 
by acting upon the auditory organs, so it may be conceived, that cer- 



the air, or vacuum between the glasses, and enter into the second glass, as 
explained in the first, fourth, and eighth observations of the first part of the second 
book. But if the second glass be taken away, the light, which goes cot of the 
second surface of the first glass into the air, or vacuum, wiU not go on forwudSf 
but turns back into the first glass, and is reflected; and therefore it is drawn 
back by the power of the first glass, there being nothing else to turn it bade 
Nothing more is requisite for producing all the variety of colours, and degrees of 
lefrangtbility, than that the rays of light be bodies of different sizes ( the leut of 
which may make a violet, the weakest and darkest of the colours, and the took 
easily diverted by refracting surfaces from the right course ; and the rest as tfaey 
are bigger and bigger, may make the stronger and more lucid colours, blue, green, 
yellow, and red, and be more and more difficultly diverted. Nothing more isie* 
quisite for putting the rays of light into fits of easy reflection and easy tnuumb* 
sion, than that they be small bodies, which by their attractive powers* or some 
other forces, stir up vibrations in what they act upon ; which vibratioiiis bdqg 
swifter than the rays, overtake them successively, and agitate them, so aa by torn 
to increase and decrease their velocities, and thereby put them into those fitSb 
And lastly, the unusual refraction of island crystal, looks very much as if it wde 
performed by some kind of attractive virtue, lodged in certun sides, both oftSie 
rays, and of the particles of the crystal, and not in their other sides; for were it 
not for some kind of disposition or virtue lodged in some sides of the particles of 
the crystal, and which inclines and bends the rays towards the coast of imnsoal 
refraction ; the rays which fall perpendicularly on the crystal, would not be re- 
fracted towards that coast rather than towards any other coast, both at their in. 
cidence, a:»d at their emergence, so as to emerge perpendicularly, by a coatnij 
situation of the coast of unusual refraction, at the second surface ; the crystal acting 
upon the ra) s, after they have passed through it, and are emerging into the air, or, 
if you please, into a vacuum. And since the crystal, by this disposition, or virtoe» 
does not act upon the rays, unless when one of their sides of unusual refraction, 
looks towards that coast ; this argues a virtue or disposition in those sides of the 
rays, which answers to, and sympathises with that virtue or disposition of the 
crystal, as the poles of two magnets answer to one another. And as magnetiiai 
may be intended and remitted, and is found only in the magnet arid in iron, so 
this virtue of refracting the pcri)endicular rays is greater in island crystal, leisiB 
crystal of the rock, and is not yet found in other bodies. I do not say, that thii 
virtue is magnctical ; it seems to be of another kind; I only say, that whateverit 
be, it is difBciili to conceive how the rays of light, unless they be bodies, f^** htfc 
a permanent virtue in two of their sides which is not in theit other sides ; and thii 



[ 123 ] 

tain particles or aggregates of particles from any matter movinp: 
with great and equal velocity may occasion the sensations of vision, 
and the other effects of the solar beams ; and the difficulty of refract- 
ing terrestrial radiant heat^ may be conceived to depend upon the 
greater size of tlie aggregated particles ; and according to the New- 
tonian hypothesis, any matter moving with considerjiblc quickness 
in right lines may be conceived capable of commuiucating an ex- 
pansive motion to the particles of bodies. 

7. If specific highly rare imponderable fluids be assumed to ac- 
count for the phsenomcna, as many must be adopied as there are 
different series of effects produced by different rays. There must 
be a matter of violet light, a matter of blue light, and so on ; and 
likewise a deoxidating ethereal matter, a calorific solar matter, and 
a calorific terrestrial matter, which is vevy contradictory to tiie usu- 
al simplicity of causes observ|ble in the economy of things ; and the 
idea likewise is rendered improbable, by experiments on solar phos- 
phori. When a mixture of calcined oyster shells and sulphur, that 
have been heated together, is exposed to the solar rays, it forms a 
good solar phosphorus, it becomes luminous, and continues so for 
some minutes in the dark ; and to wliichever of tlie prismatic rays 
it be exposed, its light is always the same, pale yellow. It is easy 
to explain the phenomenon, on the idea that vibratory motion is 
communicated to particles of tlie substance by the rays, in conse- 
quence of which, some of its own particles are slowly sent off, or 
that the particles have been formed into new aggregates, in conse- 
quence of the attraction of the substance ; but if light be supposed 
. specific in its kind, and absorbed and emitted ; then, when tlic 

widiout any regard to their position to the space, or meilium, through which they 
pus." Optics. 

May not the experiments of Die. Young, Phil. Trans. 1804, page 2, which he 
considers as proving that homogeneous light at certain equal distances, in the Ji. 
rection of its motion^ is possessed of oppo^te qualities capable of neutralizing each 
other, and of extinguishing the light when they happen to be united ; be explain. 
ed on the idea of attractive poles in opposite sides of the particles of light ? Tliat 
able philosopher considered them as favourable to the theory of undulation ; but 
if the attractions of other matter can destroy the motions of light, as in the case 
of its action on Uack bodies, may not the same result be produced by the attrac- 
tions of its psurticles for each other ? 



.iif>.i,rr.r:j. j. ^::rvj.sft.-i :o *iuft ::av-.- jiue •ar-. iiuiic ^'^ut x- X 
.'-iistti^-u Viir:-! .s not '::ft '^5-e. 

lear . int iVoni "ilie "jw \. "liiar ia''e icea le^eioTJca. -iven :akiinr OK 
.'!>/v*onian -i^finr-r it '*Tn!M.*aon xr »rantc:u .t js srnient "'Tar soct 
:/>rnJ.inannn.«i ire .nerr^iy .ir^nrnericii. W'len ine ioiar ray^ ase 

Mis '.^.enrv. 'liar, iiiiiir mcrifin la inmmmiicaie-i -q ~j.e 3articie» if 
Mc Virtv. -^ut ■vv:iet:icr uiev uiliere jq .r. or ir^ ran*vn o^F in acw 

r.r* n^fi-v-is. ic.^urat.i incijj^n "ii lecernune Tirnetiier ji iucii ca;ses ±ttt 
Li an -r.rv"i35e "^t 'v*ij>-nt . inci -iia -s -je miv ?iac aa jc ieaenaed 
•-1 v,n- ot r.7'ie cLieTnuiai vUim:;inatioe!. ':r if ziec.ianical niixEire. 
The r.i'fi -ir'viuri^r: in i ."iiinii:iti' oi i^emical "riceasea-. isaKaoH 

b'y *'AJ^f:7 Daricien at 'iie niomer.t '-£ "izeir enfirJi'^ inco chemkil 
'■.r.iry-i. Ar.y v^i.d i'jonies nuiy le zioiie ".: iziir iLriit. wiiec espoaed 

of :..'i^ lime kir^. anci 'h:.* •'.i.'^.uTZdar.ce is ii'^oiirabl^i ca the idea of 
t;*.c ii^riSH'-.^il:-/ of '..-.t^ con7ev'jicn of -zcmzion zurier into ndiact 

Mar.7 ph«r.crr.cr.a, ^r.:-h ha-:: beer. ir.TUured to CQinbLxed C^ 

ij^TxCar ro .;o £;.*r.r.ri'-i!. o? to Kt moreiy the e^ect of tisc i^nidt»crf 

'I-..*i ^'.:/%far.oo^ for. wheriC-er h*a: riies ■::•:■ toqcI a certain dcgrcf. 

,o':ii':^ v:oorf.r; iiirr:ir;o<.is ; r/ieoti of a/iirtz nibfckrd :o?eLhcr are rei- 

''.'.:':'I r i'of.-ioai ; ir:fi ^>y perc^^sion or friction, any hard bodies inaf 

. f. . ■■ c », ^ » ,, ;, ^. -♦.,*' 
» » •■. I »^' ■ ■-' ei--. -• 

»;.ir"...',; V.': LiTeUrr.ior: c: Ltr^jin '^Txlmsd and vegetable substv- 

">i i'>;'* :=i ^irr.irter!; and iM, is no more difficult to account for, 

. .r. *:■.(; f.f^K or^^d'i^ed during sirnjhr operations. 

'f /•.*; li-.^.r. "rr/itted by cerLai.- living insects appears to depend np- 

7; t.'i'i v.o.f/iori of a substance very easy of decomposition ; Arid iriy 

' ►^.r.;' .:>i or,ari;^e may be supposed adequate to the producucn of 

\>"(:u aoT/ictimcs supposed, that a specific imponderable 
, f.afiabic of producing light, is contained in oxygene gas : 




[ 125 ] 

and it has been also imagined, that such a substance exists in in- 
flammable bodies ; but the facts are contradictorr to the hrpothess. 
Iron, when heated to wliiteness, bums with amazing briJliancy in 
osfgene gas, throwing off sparks intense!? luminous ; but« when 
heated to 600" Fahrenheit, it combines slowly with the oxygene, 
producing heat without light ; the chemical change is of the same 
nature in both cases; the only difference is in its rapidity and 

enet^. 

9. The later investigations on light teach us that there is still 
much to learn with respect to the affections and motions of radiant 
matter; and this subject, when fully understood, promises to connect 
together chemical and mechanical science, and to oflFer new and 
more comprehensive views of the corpuscular arrangements of 
matter. 

In radiant matter, the particles act almost independently of the 
common laws of attraction ; and by prismatic refraction, the diffe- 
rence of their actions is determined, and it seems probable that the 
' relations of the different particles to the crystalline arrangements of 
matter, will be found connected with those powers which they pos- 
sess analogous to electrical qualities. 

If that sublime idea of the ancient philosophers, which has been 
sanctioned by the approbation of Newton, should be true, namely, 
that there is cmly one species of matter, the different chemical, as 
well as mechanical forms of which are owing to the different arrange- 
ment of its particles, then a method of analysing those forms may 
probably be found in their relations to radiant matter. Newton sup- 
posed that the luminous particles at the violet end of the spectrum 
ivere smallest in size, and those at the red end, largest in size, and 
those producing the ihtei*fllediate coldtifS, intermediate. On this 
idea, the calorific invisible particles would be the largest Ih the solar 
beam, and the calorific ^alticleS emitted hf teitestrial bodies may 
be imagined of sull greater size, so as to be incapable of passing 
through the pores of dense transparent media. The rays at the red 
end of the spectrum, in their chemical powers, tend to bum bodies, 
or to combine them with oxygene ; those at the opposite end tend 
to restore inflammability to bodies ; and negative electricity, whktf 
exercises the same function^ produce^ hydrogene gas from water; 



[ 126 ] 

and this is the lightest chemical element in nature, and may be con- 
ceived to be composed} on the corpuscular hypothesis, of the small- 
est particles. 

10. The idea that light is not a specific fluid is confirmed by some 
practical results relating to the oeconomy of light. Count Rumford 
has lately shewn, that the quantity of light emitted by a given por- 
tion of inflammable matter in combustion, is proportional in some 
high ratio to the elevation of temperature ; and that a lamp having 
many wicks very neai* each other, so to communicate heat, bums with 
infinitely more brilliancy than the Argand's lamps in commoii \ise« 






[ 127 3 



DIVISION m. 

OP EMPYREA"L UNDECOMPOUNDED SUBSTANCES, OE UN- 
DECOMPOUNDED SUBSTANCES THAT SUPPORT COMBUS- 
TION, AND THEIR COMBINATION WITH EACH OTHER. 

I. General Observations. 

1. It has been mentioned, that almost all cases of vivid chemical 
action are connected with the increase of temperature of the acting 
ix)dies, and a greater radiation of heat from them ; and, in a number 
of instances, light is also produced. See p. 51, and 92. 

The strength of the attraction of the acting bodies determines 
the rapidity of combination, and in proportion as this is greater, so 
likewise is there more intensity of heat and light. In the phlog^tic 
doctrine of chemistry, all changes in which heat aiid light are mani- 
fested were explained, by supposing that the acting bodies contained 
the principle of inflammability ; in the antiphlogistic doctrine, most 
of them have been accounted for by imagining the position or trans- 
fer of oxygene : but all the later researches seem to shew that no 
/leculiar substance, or form of matter is necessary for the effect ; that 
it is a general result of the actions of any substances possessed of 
Btrong chemical attractions, or different electrical relations, and that 
it takes place in all cases in which an intense and violent motion can 
be conceived to be communicated to the corpuscles of bodies. 

2. Many bodies which have not yet been decompounded, and which 
oannot well be conceived to contain oxygene, produce heat and light 
by their mutual chemical action : such are some metallic substan- 
cess potassium, for instance, in combining with arsenic and tellurium ; 
and sulphur and certain metals become ignited during their union. 
In naming a class of bodies by their relations to combustion^ or to 



*■ ^. 



[ 128 ] 

their efficacy in producing the phsenomena of firc^ it is only intended 
to signify that the production of heat and light is more characteristic 
of their actions, than those of any other substances; a!nd they are like- 
wise opposed to all other undecompounded substances by their elec- 
trical relations, being always in Voltaic combinations attracted tO| 
or elicited from the positive sur&ce; whereas all other known unde- 
compounded substances are separated at the negative sur&ce. Only 
two undecompounded empyreal substances have been as yet .disco- 
vered. They will be described, and their actions on each other dis- 
cussed in the two following sections. 

II. Of Oxygene Gas, 

1. Oxygene gas was discovered by Dr. Priestley, in August, 1774. 
To procure it, a quantity -of manganese(a mineral substance found in 
abundance near Exeter, and in many other places) is introduced into 
a glass retort furnished witii a ground stopper, a quantity of oil of 
vitriol (sulphuric acid) syflicient to moisten the manganese, is add- 
ed, and they are mixed -together by means ai a g^ass rod ; the hob- 
torn of the retort is then gently heated by means of a lamp^ vod tiie 
extremity of its neck introduced under an inverted cylinder fiUed 
with water in the hydro-pneumatic apparatus*. Globules of gas will 
soon rise through the water; the first portions collected must be 
thrown away, being principally the common air contained in the re- 
tort; when a quantity equal to the capacity of the retort has been 
thus disposed of, the remainder may be preserved for use; 

There are many other modes of obtaining oxygene gas; the same 
manganese heated to redness in an iron tube, such as a gun-»barrel-, 
the touch-hole of which is closed, will afford a considerable quantity 
of the substance, which may be collected by means of a tube fasten- 
ed into the neck of the barrel, and having its extremity in the hydro- 
pneumatic apparatusf. 

Nitre heated strongly in a porcelain retort, gives off oxygene gas; 
puce-coloured, or red oxide of lead offers a similar result ; and from 
any of the salts calle<l hyperoxymuriatcs, oxygene is procured by a 

♦ Sec Plate IV. fig. 2.1. t See Plate IV. Hg. 24. 



[ 129 ] 

dall red heat ; a retort of glass may be employed in the process ; and 
a charcoal fire in a small chafiing-dish. 

100 grains of the hjrperoxymariate of pctassa, afford about 1 14 cu- 
bical inches of oxygene gas, under common circumstances. 

The oxygene gas procured from nitre and the metallic substances 
above mentioned, is mixed with larger or smaller quantities of other 
permanent gaseous matter ; the gas from hyperoxymuiiate of potas- 
sa 18 free from such adulteration, and when collected over mercury, 
Gontdms nothing but aqueous vapour, from which it may be purified 
by means of the salt called dry muriate of lime, or by sticks of com- 
inon potash. The elastic fluid from nitre contains more foreign 
f^seous matter than that from the metallic oxides. The gas from 
mang^ese and sulphuric acid, when collected in the mercurial ap* 
paratus, seldom affords more tlian -^ of adulteration ; when collected 
over water, it is nuxed with from ^ to ^, in consequence of mix- 
ture with the common air expelled from the water. 
. The degree of purity of oxygene gas produced in these modes, is 
easily ascertained by filling a small curved tube closed at one end, 
with mercury, and passing into it some of the dry gas, so as to occu- 
lt about ^ of its capacity, which is measiu^d; a bit of phosphorus 
k) the proporticm of half a g^rain to a cubical inch of gas, is introdu- 
ced and made to pass into the curved part of the tube ; the phospho- 
rus is inflamed by the application of tlie heat of a spirit lamp ; at the 
moment of the expansion of the gas, the open extremity of the tube 
is closed under the mercury by the finger, and heat is applied till no 
light can be perceived in the tube ; when the tube is cool the finger 
is taken off. The mercury will instantly rise into the tube ; all tlic 
oxygene will have been absorbed, and the gas remaining, when mea- 
sured and compared with the original quantity, will indicate the im- 
purity. 

3^. Oxygene gas is distinguished from all other gaseous matter by 
several important properties. 

Inflammable substances bum in it under the same circumstances 
as in common air, but with infinitely greater vividness. 

If a taper, the flame of wliich has been extinguished, the wick 
only remaining ignited, be plunged into a bottle filled with it, the 

R 



C 130 ] 

&me m\\ be instantly rekbdled, and will be very brilliant^ and ac* 
companied by a crackling noise. 

If a steel wire, or thin file, having a sharp point, armed with a lAt 
of wood in infiammation, be introduced into a jar filled with the gaa^ 
the steel will take fire, and its combustion will continue produdng a 
mosi brilliant phsenomenon. 

The specific gravity of oxygene gas has been already referred to, 
page 63 ; it is to that of hydrogene gas, as 15 to 1 ; 100 cubical 
inches under an atmospherical pressure equal to that of 30 inches of 
mercury, and at the temperature of 60<> Fahrenheit, weigh about 34 
grains. Its power of refi*acting light, is stated by Biot and Arago to 
be to that of hydrogene, nearly as 1958 to 1000. Its capacity fi>r 
heat, according to Dr. Crawfoitl, is nearly as 4.7 to 21.4. 

Oxygene gas is slightly absorbable by water. From Dr. Henry's 
experiments, it appears that this fluid takes up -^j of its balk at 60^ 
Fahrenheit, whatever be the density of the gas. 

Oxygene gas is respirable ; a small animal confined in a jar filled 
with this gas, lives four or five times as long as in an equal quantity 
of common air; — hence it has been called vital air. 

3. The proportion in which oxygene gas unites to bodies, has been 
referred to, page 63, and the number representing it may be consi- 
dered as 15; various elucidations of the correctness of this conclu- 
sion, will be found in the following pages. 

4. Oxygene gas forms the most important part of our atmosphere. 
It is easy to prove this by many very simple experiments. 

If phosphorus be inflamed in a tube half filled with atmospherical 
fdr, in the same manner as in the experiment for ascertaining the 
purity of oxygene, a quantity of clastic matter will be absorbed equal 
to about one-fifth of the volume of the confined air, and the same 
substance will be produced as that formed by burning phosphorus 
in oxygene : the remaining elastic fluid will not support flame, and 
animals will not live in it; it is called azote or nitrogene gas; and if 
four parts of it be mixed with about one part of pure oxygene gas, 
they constitute a mixture resembling exactly atmospheric air. That 
the oxygene obtained artificially is tlie same chemical substance as 
that found in the air, is proved by the phaenomena of the calcination 
of mercury. If running mercury be preserved in ^ heat at which it 



t 131 3 

boils slowly, in a retort, the beak of which is plunged in mtrtntff 
and the process be continued for some days, there will be a gradual 
diminution of the air, and after a certain time, the remainder will not 
support flame, and a part of the mercury will be found converted into 
a red powder. It will have gained in weight, as much as the air has 
lost; and the red powder, if heated to ignition, will give ojffa quanti- 
ty of oxygene, that, added to the residual elastic substance, will re- 
constitute common air, and it will be restored to the state of mercury. 
And this oxygene, if a part of it be compared with the oxygene pro- 
cured in other modes from mineral substances, or artificial com- 
pounds, is found in no respect different; its specific gravity, refrac- 
tive power, and chemical properties, are precisely identical* 

There have been several substances proposed for ascertaining with 
facility the quantity of oxygene in air ; they have been called eudio- 
metrical substances ; and the instruments in which they have been 
employed, are named eudiometers. The solution obtained by water 
from sulphur and pearl ashes, or sulphur and lime that have been 
fused together, slowly absorbs oxygene ; a solution of tin in muriatic 
acid, has a similar property ; and likewise solutions of iron, into 
which nitrous gas has been passed till they become coloured, A. 
tube of glass graduated to 100 parts, forms a good eudiometer ; and 
when filled with air, it is plunged into any solution that will absorb 
oxygene, and suffei^ed to remain there, till the process is complete. 

It was formerly supposed that there are great differences in 
the quantity of oxygene in air, in diffsrent places, and at different 
times ; but all late researches shew that this opinion is erroneous. 

Air, analysed in different quarters of the globe, in cities, and in 
the country, on sea and land, has been found not perceptibly diffe- 
fent in composition ; the accurate proportions of oxygene and azote 
are 31 and 79. 

It has been shewn by the experiments of Dr, Priestley, Mr. Dal- 
ioDy and M. Berthollet, that different elastic fluids have a tendency 
Co rapid equable mixture, even when at rest, and exposed to each 
other on small surfaces only ; and the mixture of the parts of the 
atmosphere is constantly assisted by winds, by currents of air, and 
by all the motions taking place on the surface of the earth. 



C 132 ] 

5. In all processes of combustion in the atmosphere) oxygene ift 
either fixed in the combustible body, or it dissolves it, or forms a 
new compound with it. In respiration, as will be more fully ex- 
plained in the last part of this work, the volume of air is not chang- 
ed : but a part of its oxygene disappears, and an equal bulk of car- 
bonic acid gas is found in its place. 

As the constitution of the atmosphere constantly remains the 
same, it is evident that there must be some processes in nature) fay 
which a quantity of oxygene is produced equal to that consumed. 
One principal cause of the renovation of oxygene appears to be in 
the process of vegetation ; healthy plants exposed in the sunshine) 
to air containing small quantities of carbonic acid gas, destroy that 
elastic fluid and evolve oxygene g^s ; so that the two great classes 
of organized beings are dependent upon each other. Carbonic acid 
gas, which is formed in many processes of combustion, as well as in 
respiration, if not removed from air, by its excess would be delete- 
rious to animals, but it is a healthy food of vegetables ; and vegeta- 
bles produce oxygene, which is necessary to the existence of ani* 
mals, and thus this part of the ceconomy of nature is preserved) by 
the very functions to which it is subservient ; and the order ^s» 
played in the arrangement, demonstrates the intelligence by which 
it was designed. 

6. No other forms of matter have been produced from oxygene 
by any processes to which it has been submitted ; but it readily en- 
ters into combination, and no substance is more active as a chemical 
agent. It is known to be a constituent part of most of the acids and 
earths, and of all the alkalies except one, and the history of its com- 
pounds forms the most extensive and important part of modem 
chemistry. 

Its operations, as will be seen hereafter, ai'e connected with lamy 
of the arts ; with the processes of bleaching, dyeing, colour-malung, 
and metallurgy ; and in its various applications to the production of 
fire, it is absolutely essential to cultivation, and to the comforts and 
enjoyments of social life. 

In the phaenomena of nature, it occasions a wonderful diversity of 
effects. It is active in most of the changes taking place on the sur- 



•■V 



C 133 ] 

foce of the globe, and its constant tendency is to unite different snV 
stances in forms adapted for the purposes of organized life. 

II. Chlorine^ or oxymuriatic Gas. 

1. This elastic substance was discovered by Scheele in 1774. It 
may be procured in the hydro-pneumatic apparatus, by a process 
very similar to that first described in the last section for procuring 
•xygene gas, but the manganese is to be mixed with common salti 
and the oil of vitriol diluted with an equal quantity of water. The 
best proportions are three parts of common salt in weight, one part 
of manganese finely powdered, and two parts of oil of vitriol ; instead 
of manganese, red oxide of mercury, or puce-coloured oxide of lead 
may be used, and instead of the common salt, and oil of vitriol, a so- 
lution of muriatic acid in water (spirits of salt. C). 

2. Chlorine is of a yellowish green colour, and it is this property 
which suggested its name*. Its odour is exti'emely disagreeable. 
It is not capable of being respired, and even when mixed, in very 
small quantities, with common air, renders the air extremely perni- 
cious to the lungs. 

Its specific gravity is to that of hydrogene, nearly as 33.5 to I, 
and 100 cubical inches of it weigh at mean temperature and pres-< 
sure between 76 and 77 grains. 

It is absorbable to a certain extent by water : at the temperature 
of 60** Fahrenheit, water dissolves about double its volume, and ac- 
quires a strong acrid taste, and a disagreeable smell. 

When an inflamed taper is introduced into a phial filled with it, 
the light continues, but of a dull red colour, and a dark carbonaceous 
smoke rises from the flame. 

Many of the metals introduced into it in thin filaments, or leaves, 
or powder, take fire, and burn spontaneously at common tempera- 
tures ; such are copper, tin, arsenic, zinc, antimony, and the alka- 
line metals. 

Phosphorus bums in it spontaneously, with a pale white light, pro- 
ducing a white volatile powder. 



r 






t t3t I 



\^ SulphMr metled w siibliiafid in it^does not hum, but fbims-n'ith it 
■ Voladle red liquor. 

- Ttie gas doea not change by any action of heat or cold ; but its 
■queoUB aohition fi'cezea more readily than water, namely at obovt 

■ 40° Fahrenheit. 

■ v' Wlien freed from vapour by muriate of lime, the gas does not act 
-^t^n perfectly dry substances tinged with vegetable colours ; bat' 

wtien moisture is present in the gaa or the coloured bodies, their 
colours are speedily destroyed, they are rendered white, or brougin 
to a dull yellow ; and this last tint is almost the only one not change' 
ed by the combined action of water and chlorine. 

3. Chlorine and oxygene are capable of existing in combinatian, 
' and they form a peculiar gaseous matter. They do not unitei when 
mixed together, but when existing in ceitain solids, tliey may be 
' detached in union. 
r'.^'o make the compound of chlorine and oxygene, fayperoxymv- 
riate of potassa is introduced into a small retort of glass ; and twice 
as much muriatic acid as will cover it, diluted with an equal volume 
of water. By the application of a gentle heat, the gas is evolved, 
and it must be collected over mercury. 

I discovered this elastic substance in its pure form ui JBoUSry, 
1811, and gave to it the name of Euchlorine^, from hs btigbt jel- 
low-green colour. "- * ■-,.!>c>it 

Its tint is much more lixely than that of chlorine, 
dined to yellow. 

Its smell is very different, being not unlike that of burnt' 
■ Jt is not respirable. 

It is soluble in water, to which it gives a lemon colour 
up 8 or 10 times its volume. . "-, ;^^t 

Its specific gravity is to that of hydrogene, nearly as 33tO'*/^ii^ " 
cubical inches weigh at mean temperature and pressure bet^iraHMifr 
and 7 5 grains. ■ ■-. V-i-'A^"- 

It must be collected and examined with great care, n'd-^oMiycJV 
small quantities at a time; a very gentle heat causcK it b>' ^^Hlk' . 



[ 135 3 

BometitneB even the heat of the hand ; and its elements separate from 
each other with great violence, producing light. 

From the facility with which euchlorine decomposes, it is not easy 
t!Q ascertain the action of combustible bodies upon it. None of the 
metals that burn in chlorine, act upon tliis gas at common tempera- 
tures ; but when the oxygen is separated, they then inflame in the 
chlorine. It is easy to witiiess this. Let a little Dutch foil be intro- 
duced into a bottle filled with euchlorine, it will undergo no change, 
CUid will not even tarnish. Let a heated glass tube be applied to the 
gas in the neck of the bottle, a decomposition will take place, and the 
oxygene and chlorine will be detached from each other, and at the 
same moment the foil will inflame, and bum with great brilliancy. 

Chlorine is rapidly absorbed by mercury ; euchlorine has no ac- 
iion upon it, and chlorine may be separated from euchlorine, by agi- 
tation over mercury, and the last obtained pure. 

When phosphorus is introduced into euchlorine, it is instantly de- 
composed, and the phosphorus bums as it would do in a mixture of 
ft parts in volume of chlorine, and one part of oxygene. 

The inflamed taper, and inflamed sulphur, instantly decoropote it. 
«nd exhibit the same phenomena as in a mixture of two psju yi 
chlorine, one part of oxygene. 

That the gas is actually composed of these elements; if^ 
-causing it to detonate in a glass tube over pure mercnrr x 
Its brilliant colour, and becomes chlorine and ozygcat:. ?I 
treated in this way, expand so as to become iboai 61' jbe%^ -rnea. 
coDfiist of 40 parts of chlorine, and 20 parts of oxr^exK. 

'When euchlorine freed from water, is rcadt :& mr vfKK. vrr -ner». 
table colours, it gradually destroys them, bet itrsi pva n tzK iiua*:&. 
a tiBt of red ; from which, and 13 iSxo^fiibLIzx br vbks. kiC '.tk 
taite of its solutioo, which b scrcDgh- acrad wpppratssaa^ -& kiut -■ 
may be considered as appraxiuuuii^ i& a arjjef a ia xaryjrt^ 

4. The proportioo in which cfalansie csgoiaBn -rri *K*di;t&. 'nc* 
be learnt from the decomposzioB «f cacirjrw:: rzj&: zzTrirr-n; ii 
which is to the chlorine, w 15 to €T ia w«:2^. If rniiaonw 7» 
considered as consamng of osae pro^rarSe. « vcyu^f^ «• /«v r» 
chlorine, then 67 ^rill be tbc uunaer rgyraerr.-*g ciiiinK- *-n^'^ ^ 
most conveiueoty as bc3Dg * wi»k ziumt^^:? 1: ttQ:^^i^nsu. *v < .-* 



fH»ed Ut CMiatn two prnportions of chlorine and one of oxygcnc, 
then the number repreaentmg chlorine will bi: 33.5. It will hereafter 
be shewn ihal whichever of tbe^ ibta be assumed, the reliUioo* of 
tl)e number will harmonize with tlioae gained from various Dttiei 
combinations. 

5. Schecle considered chlorine as an element of the muriatic acid, 
and hence called it dephlogisticatcd marine acid. By that chenua, 
it was regarded as an undt^ compounded body. 

Lavoisier and Be ithollet asserted that it was a compound of muti- 
atic acid gas, and oxygcse. This idea is now universally given upi 
but some chemists in France and Scotland, conceive that it ia s ctmr 
pound of oxygeiie, and an unknown body, which they call dry muria- 
tic acid. The wcig;hl of chlorine, its absorbability by water, il» co- 
lour, and the an^ogy of some of its combinations to bodies, known M 
contain oxygene, are arguments in favour of its being a conipound; 
and it is possible that oxygcne may be one of its elements, or thU 
oxygcne and chlorine are similarly constituted. 1 have made i 
number of experiments with the hopes of detecthig oxygcnc in it, 
but without success; none of its compounds witli inflammable bo- 
dies or metals will afford this prmciple ; charcoal intensely i|[mteij 
in it, undergoes no change, nor is it altered by tlie strongest powen 
of electricity. Should oxygene ever be procured from it, some other 
form of matter, possibly a new one, will at the same lime be disco- 
vered, as entering into its constitution, and till it is decompounded, 
it must be regarded, according to the Just logic of chemistry, aa an 
elementary substance*. 

6. Chlorine has never been found pure in natttre ; but existftin 
many compounds, particularly in common salt, as is evident fHaa 
the mode of its production from that substance. It is a substance of 

■ M. M. Gay Lussac, Thenanl, and Curaudan, since 1808, have laid claim ts 
ibe ide»E of oiymurialic gia being a wmple body, and of rauriatic acid gu being 
CQiuposed of this snbswnce and hydrogene. But ihese ojjinionB wew staild 
by the illuatriom discoverer of the gas, in lT7i. In Che {epets in the PhUoM- 
phical Transaelions in which I hsve e'deavourcd to shew that it is a peculiar acid- 
ifying and Bolveni principle, I have merely followed and extended his views, and 
I referred to them iri the first paper I paUiahed on the subject. 



C 137 3 

oonndenble importance in its relation to the art of bleaching} an a|i- 
plicatioD first made by the sagacity of M. Berthollet. 

la the ancient process of bleaching, the cloths of linen and cotton, 
after being treated with alkaline li3d\'ia, to free them from resinous 
and oily matters, and in some cases with very diluted oil of vitriol, 
to cleanse them from stains produced by iron, were exposed upon 
grass to dew and air, and some weeks, or even months, were required 
to give them their perfect whiteness. 

By a warm solution of chlorine in water, they are bleached in a 
very short period ; but their texture is injured; for at, the same time 
that oxygene is added to the colouring matters, muriatic acid gas is 
formed and dissolved in the water, which corrodes the vegetable 
fibres. 

The gas has been condensed in alkaline lixivia, and in lime water. 
The substance called oxymuriate of lime is commonly used for 
bleaching; but though the solution of this substance does not injure 
ao much as tliat of the gas, yet it tends to weaken the texture of linen. 
I have found that the fluid produced by the condensation of the 
gas in water containing magnesia diffused through it, bleaches with- 
out injuring the vegetable fibre. It acts much more slowly and 
gradually than any of the other compounds employed for the same pur- 
pose, and has been applied at my suggestion in Ireland, witliin the last 
few months*, with success, in whitening printed calicoes, and, when 
properly used, it does not destroy even reds or yellows fixed by mor- 
dants. Magnesia may be easily procured from sea-water, or from 
the residual liquor of salt works; and there is a probability that this 
new bleaching fluid may, at no very distant period, come into com*^ 
xnon use. 

M. Berthollet supposed that chlorine destroyed colours by parting 
with its oxygene ; the new experiments shew that the oxygene is 
derived from the water, which is decomposed by double affinity ; that 
of hydrogene for chlorine, and of the colouring matters for oxygene. 

The salts which are called hyperoxymuriates, and oxymuriates, 
are compounds of metallic bodies with chlorine and oxygene; and the- 

* By Mr. Duff/ of Oublin, a very enlightened calico.printe% 

s 



C 138 ] 

ozygene is held in them hy a very weak attraction^ and therefore is 
easily given off to colouring or inflammable matterg. 

The great circumstance, in bleaching with these compounds, is 
that the salt remsdning after the abstraction of oxygene, should not 
act upon the linen ; linen boiled in a strong solution of the salt called 
inuriate of lime, the substance remaining in the solution, when oxy- 
muriate of lime is used) I have found is considerably weakened. So- 
lution of muriate of magnesia has- no action of this kind, and therefore 
the new bleaching liquQP can hardly be injurious to the manufiscture. 

These general views respecting chlorine, and the uses and mode 
of agency of the combinations of chlorine and oxygene, will be foun4 
to be confirmed by a number of statements, to be given in the pro* 
gressof this workf Certain conclusions have been anticipated^— but 
the most important application of chlorine could not with propriety be 
separated from its history, as an undecompounded body, though de* 
pending upon its power of detaching oxygene, which appears to be 
ihp true bleaching principle, from compounds. 



[ 139 ] 



DIVISION IV. 

OF UNDECOMPOUNDED INFLAMMABLE OR ACID1FBR0U9 
SUBSTANCES NOT METALIC, AND THEIR BINARY COM- 
BINATIONS WITH OXYGENE AND CHLORINE, OR WITH 
EACH OTHER. 

I. Preliminary ObservatiofUk 

A HE bodies to be considered in this di\'i3ion, ai*e six, tiydrogene^ 
azote, sulphur, phosphorus, carbon, and boracium or boron. A^ 
mongst these, hydrogene is distinguished from all the rest by very 
singular properties. Sulphur and phosphorus are the most analo- 
gous to each other. All these substances are capable of combining 
with oxygene, and all except azote and charcoal, with chlorine. 
They are separated in Voltaic combinations, at the negative sur&ce, 
and in their electrical relations, as well as chemical powers, are op* 
posed to oxygene and chlorine. 

II. Hydrogene Gas^ or inflammable Air* 

1 . This elastic substance was first examined in its pure form, by- 
Mr. Cavendish, in 1766. 

It may be procured in the hydropneumatic apparatus from zinc or 
iron fiUngs, by means of oil of vitriol diluted with 8 times its weight 
of water; a retort, or a bottle furnished with a tube may be used; 
BO ardficial heat is required in the process. It may likewise be 
produced by passing steam over turnings of iron heated to redness 
in a gun-barrel. 

2. Hydrogene is distinguished from all other gaseous bodies, by 
its extreme lightness. The relation' of its weight to that of oxy- 



[ 140 ] 

gene and air» has been already stated. iOO cubical inches of it at 
mean temperature, and pressure, weigh about two grains and a 
quarter. 

It is very slightly absorbable by water ; that fluid takes up -^ only 
of its volume. 

Hydrogene gas has no taste, a slight but disagreeable smell. It 
is capable of being taken into the lungs, but cannot be breathed by 
man, for more than a minute. Small anunals die in it in a much 
shorter ume. 

When an inflamed taper is plunged into a long narrow jar filled 
with hydrogene, and opened in the atmosphere, it is extingnished; 
but the gas takes fire, and bums in contact with the atmosphere. 

One part mixed with two or three parts of air explodes violendy 
by the action of an inflamed body, or an electrical spark. 

3. Hydrogene gas, as has been stated, combines with oxygeoe 
g^s, and to tliis circumstance its inflammtation in the air is owing. If 
the two gasses be pure, vfater is the only result, and the proportions 
are 2 of hydrogene to 15 of oxygene in weight, or 2 to 1 in volume. 

The union may be effected by the electric spark as described in 
page 58, over mercury, or the hydrogene may be introduced into a 
vessel full of oxygene through a narrow tube, by means of pressure, 
and inflamed by electricity, or the oxygene may be made to bum in 
the hydrogene in a similar manner*. When a stream of oxygene 
is thrown into a stream of inflamed hydrogene, the heat produced is 
very intense, and far exceeds the highest heat of our furnaces, and 
may be used to fuse bodies, intractable by any other fire raised b)' 
combustion. 

The nature of water may be shewn syntlietically as well as ana- 
lytically. 

It is separated into 2 of hydrogene in volume and 1 of oxygene in 
tlie Voltaic circuit; the oxygene appears at the positive, the hydra- 
gene at the negative metallic surfaces ; and by means of platina 
wires, hermetically sealed into glass tubes, tlie products are collected 

When 10 grabis of tlie metal called potassium are added to about 
2 grains of water in a glass tube, there is a violent action, mud^ 

• See Plate V. fig. 2^. 



[ 141 ] 

hydrogene is disengaged, and by heating the results, the operation is 
completed. The same effect is produced upon the potassium, as 
would be produced by heating it strongly in contact with a small 
quantity of oxygene ; it becomes united to oxygene, and its increase 
6f weight is in proportion to the weight of the hydrogene, as 15 to 3. 
It will be needless to dwell upon the properties of water; it is 
scarcely ever found in nature pure, usually holding saline or gaseous 
matters in solution. It becomes solid at 32° Fahrenheit, and elastic 
at 212**, and in the state of steam has been applied for the produc- 
tion of the most important mechanical effects in the steam engine. 

To describe the uses of water in the operations of nature, or to 
point out its applications to the purposes of the arts, and common 
lifey would demand a volume. Animals and vegetables depend upon 
it for their existence. Water occupies nearly two-thirds of the sur- 
&ce of the globe ; and whether existing in the ocean united to salts, 
or in the atmosphere as vapour, or poured down upon the surface as 
rain, dew, hail or snow, or collected in lakes, rivers, and springs, its 
effects are constantly connected with the order of the (economy of 
our system. 

4. Hydrogene and chlorine unite with still more readiness than 
hydrogene and oxygene. To make the combination, as has been 
stated page 62, it is only necessary to expose a mixture of equal 
parts of the two gasscs to common day light, over dry mercury, or 
in a vessel furnished with a stop cock previously exhausted. In a 
certain time, the chlorine will have lost its colour, and have combin- 
ed with the hydrogene. If the gasscs have been freed from aqueous 
vapour, there will be no notable condensation, and the result is a 
peculiar elastic fluid, muriatic acid gas. By exposure to direct solar 
light, as has been stated before, they explode ; they likewise explode 
by the electrical spark; the i*esults in this case, as I have found, are 
the same, 1 in volume of hydrogene unites to I in volume of chlo* 
rine, or 1 in weight to 3.3.5. 

The nature of muriatic acid gas may be pi-oved by analysis, as 
well as synthesis. If some pure grain tin be kept melted for some 
time, in a little curved tube containing muriatic acid gas over dry 
mercury, the tin will be converted into the same substance as that 
produced by its direct action upon chlorine, Libavius's liquor, .and 



[ 142 ] 

the hydrogene gas, when accurately measured, will be found to be 
equal to one-half the volume of the muriatic acid gas. 

Those persons who suppose chlorine to be a compound of an im- 
known body, and oxygene, conceive muriatic acid gas to be a com* 
pound of -^ of its weight of water, and the same hypothetical tub- 
stance ; but as no oxygene has yet been shewn to exist in cliloriDe, 
so no such combined moisture has been proved to exist in mumdc 
acid gas. It contains minute quantities in tlie vapour of hydnted 
muriatic acid; but no water except this can be procured from it, 
unless by substances that contain oxygene ; and the quantity proda- 
ced,is exactly proportional to the oxygene contained in the substance* 
and the hydrogene in the muriatic acid gas, and the other result it 
the same as the substance combined with the oxyg^e would produce 
directly by its action upon chlorine. 

Five grains of red oxide of mercury, heated to redness, gave off 
a cubical inch, and \ of oxygene gas. Five grains of the same sab- 
stance were made to act on muriatic acid gas by a spirit lamp in a 
curved tube over mercury; corrosive sublimate was formed, and , 
water which absorbed muriatic acid gas, and 5 cubical inches of 
muriatic acid gas disappeared ; and of these 4 cubical inches, and 
J at least, must have been decomposed by the oxide of mercury, 
their chlorine united to the metal, and their hydrogene to the oxy- 
gene ; and the additional half a cubic inch, as will appear from the 
facts about to be stated, is nearly the quantity that ought to be ob- 
sorbed by the water ; the barometer in this experiment stood at 30,3; 
the thermometer at 54° Fahrenheit. Corrosive sublimate is pro- 
duced by the direct combination of mercury and chlorine ; and the 
result of Uiis experiment can only be logically explained, on the idea 
of muriatic acid gas being composed of hydrogene and chlorine. 

For the purpose of experiments, muriatic acid gas is procured by 
the action of oil of vitriol on certain salts, such as common salt, or 
sal ammoniac. It rises without the application of heat, when the sub- 
stances are mixed together ; a glass retort should be used with a 
ground stopper, the salt sliould be in large pieces, not in powder, 
and some bibulous paper should be introduced into the neck of the 
retort, to prevent any fluid acid from soiling the mercury, over which 
it must be collected. 



...J 



C MS ] 

tmatie acid gas instantly extin^ishes flame* It reddens dry 
IB paper. When suffered to pass into the atmospherer it pro- 
s a white smoke by uniting to the aqueous vapour in the air. Its 
is intensely acid. Its smell, pungent and disagreeable. 
tie specific g^vity of muriatic acid gas is to that of hydrogene^ 
Ly as 17 to 1 ; 100 cubical inches of it weighs at mean temper- 
5 and pressure, between 39 and 40 grains. Muriatic acid gaa 
pidly absorbed by water; at the temperature of 40° Fahrenheit^ 
T absorbs about 480 times its bulk of gas, and forms solution of 
iatic acid gas in water, the specific gravity of which is 1.2109. 
he table which follows, exhibits the quantity of muriatic acid gas in 
dons of different specific gravities constructed after experiments 
e at my request by Mr. £. Davy, in the laboratory of the Royal 
tution*, the results of which I witnessed. 



%rsr*^ B««„.t«3o. 



100 parts of solu- 


OfMoriaticacid 


tion of muriatic 


acid gas in water of 




gas, parts. 


specific gravity. 






1.21 




42.43 


1.20 




40.80 


1.19 




38.38 


1.18 




36.36 


1.17 




34.34 


1.16 




32.32 


1.15 


g 


30.30 


1.14 


1 


28.28 


1.13 


e 


26.26 


1.12 




24.24 


l.U* 




22.3 


1.10 




20.20 


1.09 




18.18 


1.09 




16.16 


1.07 




14.14 


1.06 




12.12 


1.05 




10.10 


1.04 




8.08 


1.03 




6.06 


1.02 


4.04 


1.01 


202 



47.25 grains of water at 43^ Fahrenheit, barometer being at 30J2, absorbed 
grains of gas, and formed a solution of specific gravity, 1.21, and the whole 
ipitated by mtrate of silver, affoided about 132 grains of diy horn sUvqr 



»i 



s 



[ 144 ] 

The compound of water, and muriatic acid gas existing in va- 
pour in muriatic acid gas, alluded to page 106, is probably of tiie 
same constitution as the most saturated solution at the same tem- 
perature, and at 45® must contain 57.57 per cent, of water ; but in 
common cases the quantity of this vapour is too small to influence 
to any extent tlie results of experiments on muriatic acid gas ; for I 
found that 200 cubical inches of gas at 75*^ passed slowly through a 
thin tube of glass cooled to 10° below of Fahrenheit, did not in- 
crease its weight -^ of a graiq, but the deposition of fluid was very 
distinct. 

4. The number representing hydrogene, as is evident from the 
details given page 63, and those just stated, and as will appear 
from a number of other evidences, may be considered as unity. 

5. Of all gaseous substances, hydrogene is most distinctly charac- 
terized as an element ; and in its relations it is opposed to oxygene. 

Its extreme lightness, and the small quantities in which it enters 
into combination, render it unlikely that it should be resolved into 
other forms of ponderable matter, by any instruments or processes at 
present within our power. Some extraordinary phaenomena which 
have been explained in the idea of its being a compound, and which 
will be referred to towards the end of this volume, are more satis- 
factorily accounted for on the idea of its being simple, or at least a 
form of elementary matter. 

Again, 57.5 grauns of water at 44'', barometer being 30.1, gained nearly S8 
grains by absorbing acid gas, and formed a solution of specific gravity, 1^ 

Thermometer, 49° Fahi«enheit; barometer 29} 46.5 grains of water by abior. 
^ing 13.4 grains of gas gained a specific gravity of 1.114. The two last results, 
which are marked in the table, agree with those gained by calculation from the fint 
experiment. When about 150 grains of the strongest solution of muriatic add in 
water, were mixed with distilled water, both being at 63^, the temperature roK 
to 75^ ; so that the real specific gravity of solutions mixed with water, is pro- 
bably a little greater than the mean, though to no amount that can interfere vrith 
the use of the table. To find the composition of an acid of specific gravity not 
marked in the table, find the difference between the two specific gravities nearest 
to it in the table t/, and the difference between their quantities of gas 3, likewiil 
the difierence between the giyen specific gravity, and that nearest to it, c, then 
d is to Z.' : : f ; x, which added to the quantity of the lower specific gravity, is the 
-jiiantity of acid gas sought. 



[ 145 ] 

Hydrogene gas is employed for filling balloons, and its low spe- 
cific gravity renders it well fitted for aerostatic purposes. It is an 
important principle in animal and vegetable bodies ;- and exists in 
larger or smaller quantities in all organized compounds. It is the 
body which gives the power of burning with flame to all the sub- 
stances used for the (Economical production of heat and light. 

III. Of Azote ^ or nitrogene Gas. 

1. Azote was discovered by Dr. Rutherford in 1772. It may be 
procured by extracting oxygene from common air, in the manner 
described page 130. It is formed directly by dissolving animal mat- 
ters, such as glue or muscular fibre, in diluted acquafortis, or fu- 
ming nitrous acid mixed with ten or twelve dmes its weight of 
water. It may be collected over water. 

Azote extinguishes flame. It is very slightly absorbable by water ; 
that fluid, according to Dr. Henry's experiments, takes up only -^ 
part of its volume. Its specific gravity, as was mentioned in page 
63, is to that of hydrogene as 13 to 1. 100 cubical inches of it, at 
mean temperature and pressure, weigh between 29 and 30 grains. 
According to Biot and Arrago, its refractive power is 58976. 

Its capacity for heat, according to Dr. Crawford, is .7936. 

2. There are several compounds containing azote and oxygene in 
different proportions ; three of which have been already referred to, 
page 63. Their nature is more easily demonstrated by analysis 
than synthesis ; though the most impoitant of them, nitrous acid, in 
' its union with water, may be made by the direct combination of azote 
and oxygene with that fluid. 

Dr. Priestley ascertained that acid matter was formed by passing 
fslectrical sparks through a mixture of azote and oxygene over water, 
and Mr. Cavendish, by a series of beautiful experiments, proved that 
the two gasses combined with the water, and formed the same acid 
as that procured from nitre by oil of vitriol. The other compounds 
of azote and oxygene are always formed from the decomposition of 
this ^id, or some of its compounds ; but as nitrous acid exists in 
different states, its properties will be best understood after the more 
simple combinations of azote and oxygene have been described. 

T 



t 1« ] 

3. Mtroua oxi4e, the compound containing tl)<: smallest ({uaiiuty 
of oxygene, was discovered by Dr. Priestley in 1773, and named bj 
Mm'dephlogisticated Ditroua air. 

It b a gaseous body, which, as has been sUtcd, page 59, may be 

! produced by heating nitrate of ammonia; a glass retort is empU^ed 

to contain the salt ; the flame of an Argand lanip is suflicieiit to pro- 

. 'duce the gas. It may likewise be obtained during the solulioii of 

'^^OC in very weak, nitric acid ; but in this case it is not pure. 

, Nitrous oxide may be preserved over water; but it is absorbed by 
fhis fluid, which takes up -^ of its volume nearly, and, for accurate 
experiments, it sho>uld be collected in the mercurial apparatus. 

Its degree of purity may be leamt from the quantity absorbed by 
: water. 

Nitrous oxide exhibits the following properties. A taper, plunged 
' into it, bums with great brilliancy, and the flame gradually becomes 
, surrounded with a bhieisk halo. Phosphorus may be mekcd anri 
sublimed in it without inflaming ; but, when introduced into it in i 
state of vivid combustion, tlie brilliancy of the flame is greatly in- 
creased. Sulphur, and most other combustible bodies, require a 
higher degree of heat for their combustion in it than they require to 
oxygene, or in the atmosphere. 

Us specific gravity, according to my experiments, is to that of 
hydrogene, nearly as 3 1 to I . A hundred cubical inches of it U 
ipean temperature and pressure, weigh bet^veen 48 and 49 grahu. ' 

Its taste is sweetish, its odour slight but agreeable. .' '■ 

It is respirable, but not fitted to support life. I ascertained, iii 
1799, that, when it was respired, it produced effects analogous to 
those produced by drinking fermented liquors, — usually a traoueiit 
intoxication, or violent exhilaration. Individuals that differ in tem- 
perament are, however, as might be expected, differently affected:-' 

The nature of nitrous oxide is shewn by the expeiiment referred 
to, page 59. One in volume of this gas is decomposed by onfr m^ 
lume of hydrogene, water is formed, and one m volume of azots tt- 
mains. 

Or, if well-burnt charcoal be inflamed in a volume of it, by a hvTV 
ing glass, one in volume of it affords as much carbonic acid as half 
ft Tolame of oxygens, and wh«a Hub carbonic ncid U sI>a6ltoBa>.ft ro^ 



[ 147 3 

lume of azote remains ; so that it consists of 26 in weight of azote, 
and 15 of oxygene. 

4. JVttroua gas was noticed by Dr. Hales, but its properties as a 
specific elastic fluid were first described by Dr. Priestley, in 1773 ; 
it is procured during the solution of various bodies in nitric acid ; 
sugar, silver, mercury, copper, bismuth, afford it very readily. 
Filings of copper are usually employed ; and a retort, or a bottle 
having a tube inserted into it is used ; the acid (if the common acid 
of commerce) should be diluted with 6 or 8 times its weight of wa- 
ter ; the production of the gas may be assisted by a gentle heat. 

It may be collected over water, which absorbs only about ^ of its 
volume ; but for accurate purposes, mercury should be employed. 

The degree of punty of nitrous gas may be known by agitating it 
ib contact with an aqueous solution of green sulphate of iron. Ni- 
trous gas is quickly absorbed«by this substance. 

When a jar of nitrous gas b opened in the atmosphere, red fumes 
jippear. When an inflamed taper is plunged into it, the light is in- 
stantly extinguished. 

Inflamed sulphur is extinguished by it ; but inflamed phosphorus 
bums in it with great brilliancy. It cannot be made to detonate 
when mixed with hydrogene, by the electric spark. 

Its specific gravity is to that of hydrogene, as 14 to 1. A hun- 
dred cubical inches of it weigh about 32 grains. 

Whether it is respirable, or has taste or smell, cannot be ascer- 
tained, as it instantly unites with the oxygene in air, producing red 
fumes, which are nitrous acid gas. 

The composition of nitrous gas has been already referred to, 
page 59. 

It is decomposable by several of the metals when they are heated 
m it, such as arsenic, unc, potassium in excess ; it oxidates them, 
and affords half its volume of azote. In an experiment in which I 
decomposed a small quantity, by igniting charcoal in it by a burning 
glass, I found that it afforded about half a volume of carbonic acid^ 
and half a volume of azote ; so that it consists of 26 of azote to 30 
•f oxygene. 

* See page 58. 



[ 148 ] 

When it is exposed to certain bodies, such as the salts called 
sulphites, solution of tin in muriatic acid, or solutions of alkaline 
sulphurets, it is converted into nitrous oxide ; I have found that) in 
accurate experiments of this kind, two in volume of nitrous gas be- 
come one in volume of nitrous oxide ; a circumstance harmoniziiig 
precisely with their relative proportions of oxygenc and nitrogene. 

5. It has been mentioned that the red fumes, produced by the ac- 
tion of oxygene and nitrous gas, are owing to the production of m« 
troua acid gas. 

It is not easy to ascertain the exact nature of this change, as the 
substance formed acts both upon mercury and upon water ; and over 
water very different proportions of the gasses may be made to con- 
dense each other. When large quantities of nitrous gas are added 
to small quantities of oxygene, in ycssels of large diameter, from 
two to three in volume of nitrous gas disappear for one of oxygene. - 
When large quantities of oxygene arc added to small quantities of ^ 
nitrous gas in narrow tubes, the absorption is from 1 to 1.5 of oxy« 
gene in volume, and 2 of nitrous gas. From a series of experiments 
on the decomposition of nitre, and others on the mixture of nitrons 
gas and oxygene, executed with great care in exhausted vessels fur- 
nished with glass stop-cocks, I am inclined to believe that the add 
obtained over water by the condensation of mixtures of nitrous gas 
and oxygene is never fully saturated with oxygene, and that the pale 
fluid called nitric acid consists of water united to two in volume of 
nitrous gas, and one and a half of oxygene ; and this acid, according 
to its different degrees of dilution, may be made to absorb different 
quantities of nitrous gas, when it becomes yellow, orange, blue, or 
blueish green ; and in this last state it is saturated with nitrous gas. 

When two of nitrous gas, and one of oxygene freed from mobture, 
are mixed together in a vessel previously exhausted of air, they be- 
come condensed to about one half of their volume, and form a deep 
orange-coloured elastic fluid, which may be called nitrous acid gas. 

Tliis substance has the following properties : a taper bums in it 
with considerable brilliancy. Sulphur inflamed does not bum in it; 
but the combustion of phosphorus continues with great vividness. 

Tin, copper, and mercury act upon it slowly ; iron ignited to 
whiteness is rapidly cooled in it. 



[ 149 ] 

Charcoal inflamed continues to burn in it with a dull red light. 

When a portion of water is exposed to it, there is a rapid absorp- 
tion) and the water gains a tint of green. 

Its smell is very disagreeable, its taste sour ; when applied to 
animal substances, it renders them yellow ; it reddens litmus paper. 

Calculating from the condensation, the specific gravity of nitrous 
acid gas is to that of hydrogene, as about 28 to 1 ; and 100 cubical 
inches of -it weigh 65.3 grains, at mean temperature and pressure. 

6. I have attempted to procure a permanent elastic fluid, consist- 
mg of two parts in volume of nitrous gas, and 1.5 oxygene, by mix- 
ing oxygene in excess with nitrous gas ; but the condensation was 
always such as to indicate the formation of nitrous acid gas, and the 
colour was deep orange ; so that the existence of nitric acid as a 
pure bodyy consisting of 1 .5 of oxygene and 2 of nitrous gas, is pro- 
blematical ; the gaseous combination of nitrous gas and oxygene 
I>robably always contains 2 of nitrous gas, and 1 of oxygene ; and 
tome basis seems necessary for the union of two of nitrous gas and 
1.5 of oxygene ; such as water, alkalies, or oxides. 

M. Gay Lussac supposes that there is a compound of three of ni- 
trous gas*, and one of oxygene, capable of combining with water and 
(ilkalies without decomposition. I have tried many experiments on 
this subject, but have never been able to make a strong coloured 
iU^uafortis containing more than 2 of nitrous g^s to 1 of oxygene in 
Volume ; when nitrous acid gas is passed into alkaline solutions, a 
portion of nitrous gas is always evolved ; and when one in volume of 
Oxygene is added to two of nitrous gas, and dry azote introduced to 
mark the condensation, no change takes place on the mixture of the 
^s with fresh portions of dry nitrous gas. 

jlqu<^forti9y or nitric acidj is procured for the purposes of chemis- 
try by the distillation of nitre and oil of vitriol ; about 2 pai*ts of nitre 
^hoiild be used to 1 part of oil of vitriol, and the retort heated in a 
sand bath connected with a receiver kept cool by moistened clotlis. 

* It is stated that this combination can only be made over a large surface of wa- 
tety which shews either that the air in the water is concerned in the condensation, 
or that the water itself absorbs nitrous gas : the size of the vessel can have no influ- 
ence on the compound formed, and it is supposed by M. Gay Lussac, readily ab- 
sorbable by water. Mem. D'Arcueil, T, II. page 241. 




I 150 ] 

The acid thus obtained is usually coloured, but becomes pale by ex- 
posure to air. If the nitre is dry, its specific gravity is from 1.590 
to 1.55. This substance acts with great violence on all the metab 
anciently known, except gold and platina, and causes volatile oils to 
inflame. When it is passed through a porcelain tube heated to red- 
ness, oxygene is given off from it, and nitrous acid gas ; and the 
same effect is produced upon the residual acid, as if it had been 
mixed with water ; so that it is proved by this experiment to be com- 
posed of nitrous acid gas, oxygene and water ; and 4, in volume of ni- 
trous gas, and 2 of oxygene gas condensed in water, I find, absorb 1 
in volume of oxygene to become nitric acid. 

7. To enter upon a description of all the expeiiments that have 
been made to ascertain the quantities of water in acids of different 
strengths^ would be unfitted to the nature of an elementary treatise* 

From my own experiments compared with those of Kirwan, Wen- 
zel, and BerthoUet, I am inclined to believe that the strongest addi 
contain from 14 to 15 per cent, of water, and according to the pia> 
ciples of the French nomenclature, they ought to be called Aydrth 
nitric acids, ■ 11; 

Aquafortis, or hydm-nitric acid, when its specific gravity is bekv K 
1 .4, strengthens by being boiled ; when stronger than 1 .45, it becomef n 
weaker by boiling. According to Mr. Dalton, the acid of 1.42 dii- 
tills unaltered at 248*^ Fahrenheit. It is probable that the add of 
1.55 consists of one proportion of water and one of acid, and that \h 
which rises unaltered at 348*^ of one proportion of acid and two of 
water. 

If nitrous gas be considered as represented by 56, that is, by oofe 
proportion of azote, and two of oxygene, 26 and 30, then nitrous acid 
gas will be represented by 86, or one of azote, 26, and four of oxy- 
gene, 60; and 101 will be the number for the add contained in the 
pale adds, and in the salts caUed nitrates, and it will conabt of ose 
of azote and five of oxygene. 

And the strongest acid will contain 17 water and 101 acid, and the 
acid of 1.42, 34 water and 101 acid. 

Hydro-nitric acid is of great use in many of the common arts. It 

employed in medicine, for dissolving metals, for etching, for mak- 



«] 



C 151 ] 

ing compounds used in dyebg, and it is one of the constituent parts 
of nitre, a substance essential in the manu&cture of gun-powder. 

S» Azote and chlorine have no chemical action on each other in 
any circumstances to which they have been hitherto exposed. 

I caused the Voltaic flame from 1000 double plates to pass through 
• mixture of them in a close vessel for some minutes; but the azote 
underwent no change, nor was any combination effected. 

9. Azote and hydrog^e exist in combination in ammoma or the 
volatile alkali. It is not easy to produce their union, yet when azote 
is exposed to moist substances giving off hydrog^e, a tittle ammo- 
nia is found after some time in the water ;i— for instance, when azote 
is placed in contact with moist iron filings above mercuiy. Priest- 
ley first procured ammonia in its pure form; and his experiments, 
and those of Scheele, repeated and illustrated in an elaborate manner 
by BerthoUet, led to the knowledge of its elements ; indeed the last 
chemist must be considered as the true discoverer of the composition 
-of ammonia. 

: To procure ammcMiia, equal parts of well burnt dry lime and dry 
^aalammoniac or muriate of ammonia, are heated in a retort of glass, 
the beak of which is plunged under dry mercury. Graseous matter 
comes over, which when the common air of the retort has been all 
expeUed, must be collected in inverted jars filled with mercury. 
' Ammonia at common temperatures is a permanent gas; according 
to Guyton de Morveau it becomes a liquid at about 70 below of 
Fahrenheit's scale : but his experiments were made in glass balloons, 
and the conclusions drawn from the appearance of fluid; so that the 
evidence, though strong, cannot be regarded as perfectly satisfectory, 
as ammonia contains vapour which must be condensed to a great ex- 
tent by so int^ise a cold*. 

The specific gravity of ammonia is to that of hydrogene, nearly as 
8 to 1. 100 cubical inches of it weigh at mean temperature and 
pressure about 18 grains. 

When an inflamed taper is plunged into a jar of ammonia the 
light is extinguished ; but a slight inflammation of the gas occurs 
where it is in contact with air. 

• Annales de Cbimie, XXIX. page 292. 



[ 152 ] 

Its taste is extremely acrid : it cannot indeed be safely vpp] 
the organs of taste or smell except when mixed with much coi 
air. It is the principle wlfich gives pungency to the commci 
Crete vdatile alkali. 

It instantly reddens paper tinged with turmeric^ and gives a 
colour to most vegetable blues and reds ; and this property, m 
other properties, characterise it as an alkaline body. 

It is rapidly absorbed by water. At the temperature of 50% i 
a pressure equal to 29.8 inches, water, I find, absorbs about 
times its volume of gas, and becomes of specific g^vity .875. 

The following table c<Hitaining approximations to the quanti^ 
ammoniacal gas in aqueous solutions of different specific gnn 
was constructed after experiments made with great care fin 
purpose. 



100 pans 

gm • ^ 




Of Ammo- 


ofspeafic 




nia. 


gravitjr. 






•8750 


32.5 


8875 




29.25 


9000 




26.00 


9054* 




25.37 


9166 


e 

1 


22.07 


9255 


19.54 


9326 


o 


17.52 


9385 


sJ 


15.88 


9435 




14.53 


9476 




13.46 


9513 




12.40 


9545 




11.56 


95rJ 




10.82 


9597 




10.17 


9619 


9.60 1 
9.50 1 


9692* 



The constitution of ammonia may be eadly demonstrated by 
ly tical experiments ; it is decomposed by electrical sparks, or b^ 
ing passed through a tube heated to redness ; its volume is inc 
ed, and it becomes hydrogene and azote. 

\t three results marked by the asterisk, were gained by experiments 
nben Ify c»lcuUtioiu 



[ 153 ] 

Mi Berthollet) jun. conceives that its volume is doubled when \t 
is decomposed over mercury by electrical sparks. In Dr. Henry's 
experiments and those that I have made^ the expansion is a little 
less ; but this is probably owing to the unavoidable imperfection of 
the process. I once thought that a small quantity of water was 
formed in the operation, but very delicate experiments have convin- 
ced me that this is not the case. I decomposed a quantity of ammo- 
nia by electric sparks in a close vessel, in which its elements could 
not expand, and yet no moisture was deposited. 

In the most accurate experiments in which the hydrogene has 
been separated from the azote by successive detonations with small 
quantities of oxygene, the volumes have been 3 of hydrogene to 1 
of nitrogene, so that ammonia consists in weight of 3 of hydrogene 
and 1 3 of nitrogene, and supposing the number representing hydro- 
gene unity, the same number is gained to represent azote as from 
the proportions of the elements in its compounds with oxygene ; and 
ammonia consists of one proportion of azote and six of hydrogene, 
and is represented by 32. That all these conclusions are correct is 
shewn by the decomposition of the compound made from nitric acid 
and ammonia. 

. When this salt, which is called nitrate of ammonia, is exposed to 
a heat gradually raised, it is decomposed into water and nitrous ox- 
ide ; and this could not happen unless it were constituted by definite 
proportions, which must be 101 of acid and 32 of alkaline matter; 
^or 6 of hydrogene require 45 of oxygene to produce water, and 53 
of azote, i. e. 26 in the acid, and 26 in the alkali, require 30 of oxy- 
gene to produce nitrous oxide. 

Ammonia is employed in medicine, and its compounds are used 
10 processes of dyeing, and in some of the metallurgical arts. 

10. Azote has not as yet been resolved into any other forms of mat- 
ter. I volatilized the highly combustible metal potassium in azote 
oyer mercury, and passed the Voltaic fiame of 2000 double plates 
through the vapour ; but the azote underwent no change. I have 
made many other attempts to decompose it, but they have been un- 
8|iccessful. 

The strongest arguments for the compound nature of azote are 
4^nved from its sU^ht tendency to combinaticm ; and from its being 

u 



[ 154 3 

found abundantly in the organs of animals which feed on substances 
that do not contain it. 

Its uses in the oeconomy of the j^lobe are little understood ; this 
likewise is favourable to the idea that its real chemical nature is as 
yet unknown, and that it is not actually an undecomposable substance. 

It would appear that azote and oxygene combine slov^ly undep 
certain circumstances in natural opcimtions, when lime or alkaline 
substances are present ; thus nitrous salts are produced in nitre beds, 
in warm climates, and the process is assisted by, or the combination 
formed during the fermentation of animal and vegetable substances. 

' HI. OfSulfifmr. 

1. Sulphur is a well known substance, found native in many parts 
of the world, and it may be procured by the distillation of the mine- 
ral, called pyrites. 

It is brittle, moderately hard, and of a yellowish colour, and has a 
peculiar taste and smell. It is a nonconductor of electiicity. Its 
specific gravity is 1990. It is often found in regular solid forms, 
usually octohedral, when it is more or less transparent. Its power 
of refracting light, accordhig to Dr. Wollaston, is to that of water as 
.204 to .1336: its capacity for heat is stated to be as 1.9 to 1. It 
fuses at about 220° Fahrenheit, and volatilizes slowly even before it 
fuses ; at the temperature of 560° it becomes an elastic fluid, and in 
this state inflames if in contact with air, and bums with a pale blue 
flame. 

2. If sulphur be heated above 300° Fahrenheit, it gradually be- 
comes I'lick and viscid, when if it be poured into a bason of water, it 
will be found of a red colour, and ductile like wax. In this state it 
is used for receiving impressions of seals or medals. Its specific 
gravity is increased, according to Dr. Thomson, to 2325 during this 
process ; from which it seems probable that its parts undergo a new 
arrangement, and approach nearer, than in its common crystalline 
form. It has been j>upposed that the change depends upon its com- 
bininj^ with oxygcnc ; but in some experiments made expressly to 
ascertain il.is poiiit, it was not found that any oxygene was absorbed 
when sulphur was long kept heated in contact with it in close ves» 



[ 155 } 

sels, and I have observed after Dr. Irvine, jun. that the change oi 
colour takes place independent of the presence of air. 

3. The only well known compound consisting of sulphur and ox- 
ygene alone, is a gaseous substance, called in the modem nomen- 
clature, sulfihureoua acid gas. It may be procured by heating sul- 
phur in oxygene gas ; the experiment may be peiibrmed in a glass 
retort, and the sulphur mflamed by a spirit lamp ; it burns with a 
beautiful violet iiame, and if the oxygene g^s has been carefully 
freed from water, sulphureous acid gas will be the product. It may 
be formed likewise by heating mercury or copper fiiuigs, in oil of 
vitriol, and collected over mercury. 

Sulphureous acid gas has a very disagreeable smell. It is the 
smell of burning sulphur. It reddens vegetable blues, and gradu- 
ally destroys most of them. It whitens many animal and vegetable 
substances, silk and straw for instance, and hence the vapours of 
burning sulphur are employed in bleaching. 

Its specific gravity is to that of hydrogene as 30 to 1., and 100 cu- 
bical inches of it at mean temperature and pressure, weigh about 
68 gimns. 

It is absorbed by water ; this fluid takes up about 30 times its 
bulk, gains a nauseous subacid taste, and, according to Dr. Thomsony 
becomes of specific gravity 1.0513. 

That sulphureous acid gas consists of sulphur and oxygene, is 
evident from the phaenomena of its production by combustion. 

In several experiments in which I burnt sulphuf, procured from 
iron pyrites out of the contact of air or moisture, in dry oxygene 
gas over mercury, I found that the volume of the oxygene was very 
little altered; the condensation was never more than ^, and seldom 
so much as •^, and I am inclined to attribute the loss to the forma- 
tion of a little oxide of sulphur, or to a little hydrogene loosely com- 
bined with the sulphur, so tliat there is every reason to believe that 
sulphureous acid is Constituted by sulphur dissolved in a volume of 
oxygene. 

This conclusion is confirmed by some experiments on the action 
of cinnabar, which consists of mercury united to sulphur, and stfl- 
pliur itself, on metallic oxides. 



Two equ&l quantities or red oxide of mercuiy, each w^gMng 14 
grains, were lieated, one alone, the other mixed with sulphur. They- 
afibrded nearly equal volumes of gas. One, which equalled 2 cubi-' 
Cal inches and ^, ivas oxj-gcne, the other, which equalled 2 cubicd. 
tnches and -^, was pure sulphureous acid ^s. Similar experiments 

: ♦'ere itiadci cinnabar being Bubstituied for sulphur, with like results. 
If the specific gra\ilie8 of sulphureous acid gas and oxygene be 
compared, and the last subtracted from the first, it will appear that 
sulphureous acid consists nearly of equal parts of oxygene aad sul- 
phur by weight. 

4. If a solution of soipliurcous acid gas ia water be exposed ta 
the air, it loses its peculiar flavour, and becomes strongly sour; 
ftnd experiments on tlic action of the solution on air, shew tbat oxy- 

. gene is absorbed. 

' Sulphureous acid gas is easily driven off from water in tfie re* 
cent solution, hut after it has been changed by exposure to atr, wa- 
fer only rises when it is heated ; and if the evaporation is carried wi 

■ lill the temperature is 546", the residuum is found to be the same 

, substance as oil of vitriol ; notliing but water will have been gtvCB 
off; and therefore oil of vitriol contains sulphur combined «ilfc' 
thore oxygene than in sulphureous acid. That it likewise contains' 
water, is shewn by another experiment, ivbich, if made with ac- 
turacy, affords perfect evidence of its nature and composition. Lot 
a porcelain tube be healed red, and the strongest oil of vitriol passed' 
through it m vapour, a part of it will be decompounded, the gaseous 
[jroducts will be two parts of sulphureous acid gas, and one part of. 
bxygenc gas; and the fluid product will be a weaker acid, stichal 
Would be produced by diluting the acid which is the subject of ex- 
periment. ^ 
The comjxnmds made by adding oil of vitriol to 'dte «&ril^. 

t«nl», free, as fer as our knowledge riirnln, fi mi. t^i>»j'<i||l 

tnqistute when tiiey ne heated to redness, and if tiie-*]ata^^'«K( 
water in the strongest tul of vitriol, be estimated ^'m'-'riri ililinjH' 
Vt {his kiud, it may be concluded that it contains aboot 19 pti 1 Hm 
tif 'Water; md Its compositjon may be thus expressed, 30«f ttiltibft). 
4$ of oxygene, and -17 of water, . ..... ^ 



C 157 ] 

In the common process of manufacture^ oil of vitriol is made by 
huming sulphur mixed with alx)Ut \ of its weight of nitre in pans 
of laron or lead communicating with a chamber of lead, the bottom 
of which is tovered to the deptli of several inches with waleT» The 
true Uieory of this process is not given in any chemical book. 

The sulphur by burning, forms Sulphureous acid gas, and the 
acid in the nitre is decomposed, giving off nitrous gas; this coming 
in contact with the oxygene of the atmosphere, produces nitroHS 
acid gas, wluch has no action upon sulphureous acid, to convert it to 
sulphuric acid, unless water be present, and if this substance be 
only in fi certfun proportion, die water, the nitrous acid gas, and the 
sulphureous acid gas combine, and form a white crystalline solid. 
By the large quantity ^ water usually employed, this compound is 
instantly decomposed, oil of vitriol formed, and nitrous gas given 
off, which in the air again becomes mtrous acid gas, and the process 
continues according to the same principle of combination and de- 
composition, till the water at the bottom of the chamber is become 
strongly acid. It is easy to prove the tnith of these reasonings; 
let dry sulphureous acid gas, and nitrous acid gas be mixed 
together, by suffering ihe sulphureous gas to pass into ja glass globe 
^fflrtially exhausted, add contsuning nitrous acid gas. There will be 
no action between the gasses. But if a drop of water be introduced, 
there will be an immediate condensation, and a beautiful white 
crystalline solid will line the interior of the vessel. Whereas if the 
globe contain plenty of water, nitrous gas will be given off with 
great violence, and the water will be found to be a solution of oil 
of vitriol. 

In the solid crystalline compound, it is evident, from the products 
of its decomposition by water, there must be four volumes of 
sulphureous acid gas, and three of nitrous acid gas, probably in two 
or three proportions with a single proportion of water ; for nitrous 
acid gas contains ^ of its volume of loosely combined oxygene, and 
sulphureous acid gas requires half its volume of oxygene to become, 
when condensed in water, solution of oil of vitriol. 

Mr. Daiton, who has adopted M. M. Clement's and Desormes* 
idea of nitrous acid gas being decomposable by sulphureous acid 
g^s, which is not correct, supposes that there is a solid sulphuric 



' t^d> the oxy^ne in which is to ihat in sulphureous acid, as 3 to ^; 
. but the body which he supposes to lie sulphuric acid is the crysutl" 
line substance, the nature of which is demonstrated above; and no 
substance to which the name of pure sulphuric acid ought to be 
. giveU) i. e. a substance consisting of 30 of sulphur and 45 of oxf- 
gene, has yet been discovered in an insulated state. 

The term sulphuric aciili is improperly applied to the strongeU 
eil of vitriol ; this aubstanee, according to the principles a£ tbe 
French nomenclature, ou;5ht to be called kydrosulfihurii: add. 

The oil of vitriol of commerce, which is of specific gravity l.Mj 
rises in vapour at about 550° Fahrenheit, and distils unaltered; 
whereas weaker acids, by being boiled, lose water, and arc brought 
to this state of concentratbn. There is a diluted add of specific 
gravity 1.78, which congeals at any temperature below 46° Pahren- 
. heit. It is very curious, as Mr. DaJton has stated, that this acid con- 
tains exactly twice as much waiter as the acid of 1.35. It is com- 
posed, according to my experiments] of 30 of sulphur, 45 of oxjr- 
genc, and 34 of water. 

Pure oil of vitriol is a corrosive substance^ It acts with gresl 
energy upon animal and vegetabfe matter. It rapidly attracts 
moisture from the air, and produces much heat when mixed with 
water. It reddens vegetable blues; and acts with great violence 
upon alkaline substances, and upon certain earths and metallK 
«xidefi; and neutral salts are produced by the union of its aqlphiK 
and oxygenc with these bodies. 

The number representing sulphur, as learnt from the constituiioo 
of sulphureous acid gas, is nearly 30; and as this gas contains tw» 
proportions of oxygene twice 15, it would seem probable that an 
oxide of sulphur may exist, consisting of 30 of sulphur, and IS of 
oxygene. 

I have examined some highly coloured specimens of SiciGw 
sulphur, which seemed to contain a little oxygene, and, as has bees 
just stated, it is possible that a little oxygene may be condeDsed,io 
the combustion of sulphur in the residuum ; but as yet no body ii 
known that can wth propriety be called oxide of eulflliw. 

5. Sulphur and chlorine are possessed of a chemical attraction fiw 
each other. The first cembinatioii of them was made by Dr. Tbom> 



[ 159 3 

' iVon in 1804, by passing chlorine over flowers oi sulphur* It mkf 

' he made more expeditiously by heating sulpimr in a retort HUed 

''' "With chlorine. The sulpimr and the chlorine unite and form a fluid 

" . 'Mibstance, which is volatile below 200^ Fahrenheit, and distills hito 

the cold part of the retort. This substance, seen by reflected light, 

. appears of a red colour, but is yellowish green, when seen by trans- 

"tiiitted light. It smokes when exposed to air, and has an odour 

'Somewhat resembling that of sea weed, but much stronger; it 

effects the eyes like the smoke of peat. Its specific gravity, uccord- 

'ing to Dr. Thomson, is 1 .6. 

« ;- It does not redden perfectly dry paper tinged with litmus ; when 

. ' it is agitated in contact with water, the water becomes cloudy from 

."the appearance of sulphur, and strongly acid, and it is found to con- 

■ lain oil of vitriol. 

■ According to my experiments, 10 grains of pure sulphur absorb 

. nearly 30 cubical inches of chlorine; so that the compound contains 

--^^bout 30 of sulphur to 68.4 of chlorine; 30 of sulphur to 67 of 

chlorine, would give one proportion of sulphur to two of chlorine ; 

^hich, there is every reason to believe, must be the just estimation; 

4br my experiments were made in retorts luriilshed with metallic 

•Btop-cocks, by which a little chlorine must have been absorbed. 

The compound formed in the manner above described cannot be 
made to unite to more chlorine ; but I find it dissolves a considera- 
ble portion of sulphur by heat, and becomes of a tawney yellow 
colour. 

Dr. Thomson called this substance sulphuretted muriatic acid, 
but there is no proof that it conuuns muriutic acid. Accordinjr to 
an idea which I ventured to propose in the Philosophical Transac- 
tions for 1811, that of calling the compounds of chlorine by the 
name of their bases, with a termination in " ane," its name would be 
Mulfihurane. 

6. Sulphur and hydrogene combine. Their" union may be effected 
by causing sulphur to sublime in dry hydrogene in a retort. There 
is no change of volume: but only a part of the hydrogene can be 
combined with sulphur in this mode of operating. 

The gaseous compoiuid of sulpimr and iiydro^jene was discovered 
hy Scheele, in 1777. It is usually made by the action of diluted 



\ 



V 



C 160 3 

sulphuiic acid upon a mixture of three parts of iron filings, and two 
parts of sulphur that have heen ignited together ; for the purposes 
of accurate experiments, it should be collected over mercury. 

Sulphuretted hydrogene inflames when a lighted taper is brouglit 
in contact with it, exposed to the air : it bums with a pale blu« 
flame, depositing sulphur. Its smell is extremely fetid, resembling 
that of rotten eggs. Its taste is sour. It reddens vegetable blues. 
It is absorbable by water ; that fluid takes up more than an equal 
volume of the gas. Its specific gpravity, according to M. M. Gaj 
Lussac and Thenard, is to that of air as 1.1912 to 1. From my ex- 
periments, it would appear to be a little less ; but I am inclined to 
adopt the results of the French chemists ratlier than my own, as their 
gas was weighed in larger quantity, and dried. Its weight to that 
of hydrogene may be considered as 16 to 1, and 100 cubical inches 
#of it, at mean temperature and pressure, weigh between 36 and 37 
grauis. 

The composition of sulphuretted hydrogene is demonstrated bj 
the change produced in it by electricity ; if platina wires be ig^ted 
in it by the Voltaic apparatus, it is rapidly decomposed. Sulphur 
is deposited, and an equal volume oT hydrogene remains ; th^ auQe 
change is effected more slowly by electrical sparks. 

The proportion of its elements are shewn to be the same, both 
by the analytical and synthetical experiments. They must be 15 of 
sulphur to 1 of hydrogene ; and the results give as nearly as possible 
the same number representing sulphur, as its compounds with oxy* 
gene and chlorine : and sulphuretted hydrogene may be considered 
as consisting of two proportions of hydrogene 2, and 1 of sulphuri 
30. 

This body combines with an equal volume of ammonia ; and 
unites to alkalies and oxides ; so that it has all the characters of an 
acid. 

7. There is another compound of hydrogene and sulphur, the pro- 
portions of the elements of which have not yet been accurately as- 
certained ; but it probably will be found to contain at least one pro- 
portion more of sulphur. 

It may be formed by passing sulphur over charcoal ignited in a 
porcelain tube ; the experiment must be made with the exclusicMi of 



C 161 ] 

air. It is a fluid body, and was discovered by Lampadius, in 1796j 
and called by him alcohol qf sulfihur. Its colour is greenish yellow. 
Its taste pungent, its smell peculiar, its specific gravity is 1.3. It is 
very volatile. It does not mix with water. It burns with the same 
facility as spirits of wine. It dissolves sulphur with great facility, 
by the assistance of heat ; and when the saturated solution of sul- 
phur in this substance is exposed to air, as the alcohol of sulphur 
evaporates, crystals of sulphur arc deposited. When it is exposed 
to platinum ignited by the agency of Voltaic electricity, it gives off 
sulphuretted hydrogene. This, and the phaenomena of its combus- 
tion, demonstrate its nature ; for, when it burns in contact with oxy- 
gene, the products are sulphureous acid and oil of vitriol. 

When quicksilver is heated in the vapour of alcohol of sulphur, a 
compound of sulphur and quicksilver is formed, and sulphuretted 
iiydrogcne disengaged. 

8. Sulphur has no chemical attraction for azote, at least no com- 
pound of these bodies has as yet been formed. 

9. Sulphur has been placed amongst the undecompounded bodies, 
because as yet nothing certain is known respecting its elements. 
When Sicilian sulphur was fused and exposed to the action of pla- 
tina points intensely ignited by Voltaic electricity, excited by 1000 
double plates, permanent gas was given off from it, which proved 
to be sulphuretted hydrogene : a small quantity of sulphuretted hy- 
drogene is given off likewise during the action of copper filings upon 
sulphur; and the mode of the formation of alcohol of sulphur proves 
that sulphur or charcoal, or botli, contain hydrogene. It may, how- 
ever, be questioned whether hydrogene is essential to the constitu- 
tion of sulphur. Sulphur may possibly contain, in its common forms, 
a little moisture, or a little of a solid compound of hydrogene and 
sulphur ; and till the gas can be separated from it in definite pro- 
poruon, and be proved to be combined with some other matter, no 
accurate conclusions can be formed upon the subject. 

Sulphur is employed in medicine, particularly as an external ap- 
plication in cutaneous complaints. Its use in bleaching has been al- 
ready referred to. Its most important application is in oil of vitriol, 
and the compounds formed from it, which are used in various pro- 
cesses of dyeing and calico-printing. 



[ 162 3 



IV. Of Phosiihorim, 

1. Phosphorus was discovered by Bi^andt iii 1669. It may \k 
made by the following process. 

A hundred parts of burnt bones in powder are to be mixed with 
40 parts of oil of vitriol, and they are to be suffered to remun in con- 
tatt for a couple of days, the mixture being frequently stirred. The 
whole is then to be poured upon a filtre of cloth, and the liquor 
that passes through is to be added to a nitrous solution of lead ; a 
white powder will be formed ; this must be mixed with about | of 
its weight of charcoal powder, and exposed to a strong red heat b 
a porcelain retort, the beak of which is plunged in water ; much 
gaseous matter will come over, some of which will inflame aponta- 
neously, and at length a substance will drop out of the neck of die 
retort, and congeal under the water, which is phosphorus. It may 
be purified by melting it in water, and passing it under water through 
chamois leather. 

3. Phosphorus is semi-transparent, and of a yellowish colour. It 
is as soft as and more ductile than wax. It is insoluble in water. 
Its specific gravity is about 1.77. It melts at the temperature of 
90^, and boils at about 550°. 

When phosphorus is exposed to air at common temperatures, it 
emits a white smoke, which appears luminous in the dark. This 
depends upon its combining with oxygene, and forming an acid 
which unites to ihe aqueous vapour in the atmosphere, and they fall 
down in the fluid form. Phosphorus, I find, does not smoke in air 
perfectly dry ; and in this case the acid adheres to it, and in a short 
time prevents it from being luminous. 

When phosphorus is heated to about 148°, it takes fire, and bums 
with intense brilliancy, ihrowh.g off dense white smoke, which is a 
stror.g solid acid that soon becomes liquid by attracting moisture 
from the air ; and a red substance usually remains. 

3. The manner in which phosphorus acts upon air, as has beeo 
shewn, page 130, proves Uiat it is capable of comlnnhii^ ^vith oxv- 
gene ; and there is every reason to believe in at least three propor- 
tions. 



[ 163 ] 

When phosphorus is inflamed in oxygene gas over mercunry and 
the white substance produced strongly heated, the oxygene bein); 
in excess, for ever)- grain of phosphorus bumt, four cubical inches 
and a half of oxygene gas are absorbed. Tiie substance so procured 
is called phosphoric acid. It becomes fluid at a red heat ; it is not 
volatile even at a white heat. It has no smell ; its taste is intenselv, 
but not disagreeably acid. It dissolves in water, producing great 
heat ; and its saturated solution is of the consistence of syrup. It 
acts upon, and corrodes glass, and imitcs to alkalies and oxides. 

4. When phosphorus is heated in highly rarefied air, three pro- 
ducts are formed from it : one is phosphoric acid ; one is easily vo- 
latile, and appearing as a white powder ; and the otlier is a red solid 
comparatively fixed, and requiring a heat above that of boiling water 
for its fusion. The volaulc substance is soluble in water, and gives 
it acid properties. It contains less oxygene than phosphoric acid \ 
for it bums and becomes fixed when heated strongly in the air. Its 
taste is sour, with a peculiar pungency, and it emits a smell not un- 
like that of garlic. It is mixed with phosphorus, but is principally 
the substance which, according to the Fi'ench nomenclature, should 
be called phosphorous acidy and which, in chemical works, is inac* 
curately described as a fluid body. The red substance requires 
less oxygene than phosphorus to convert it into phosphoric acid, 
and must be considered as an oxide of phosphorus. 

I have never been able to procure phosphorous acid by combustion 
free from admixture or combination with other substances. In the 
common mode in which it is said to be obtained, namely, by expos* 
ing phosphoinis to free £ur, there is always a large quantity of phos* 
phoric acid formed. 

A pure solid hydro-phosphorous acidy that is, a combination of i,t 
with water, may, I find, be produced by the following process. 

Phosphorus is sublimed through corrosive sublimate in powder in 
a glass tube ; a limpid fluid comes over, which must be mixed with 
water, and the solution heated till it is of the thickness of syrup. It 
is a combination of water and pure phosphorous acid. It reddens 
vegetable blues, and combines with alkalies, and has all the charac- 
ters of a strong acid. It forms a white crystalline solid on cooling. 

It becomes solution of phosphoric acid slowly when exposed to 



[ 164 ] 

air, absorbing oxygenc. When it is gently heated, it takes fircj and 
bums with great brilliancy, emitting globules of gas that inflame ia 
contact with air ; a red oxide of phosphorus is deposited in the htitr 
torn of the vessel, and solid phosphoric acid is fonmed. 

The substance produced by passing phosphorus through corrosdTe 
sublimate, as will be immediately shewn, is a compound of phcspbo- 
rus and chlorine ; and, when it acts upon water, hydrogene is af- 
forded to the chlorine, and oxygenc to the phosphorus ; there are 
no products but muriatic acid gas and phosphorous acid, and the 
quoniiiy of hydrogene in the muriatic acid gas formed, being known, 
tlie quantity of oxygene in the phosphorous acid is likewise known. 
By two experiments made with great care, in which the quantity of 
chlorine in the liquor from tlie phosphorus and corrosive sublimatei 
was estimated by its combination with silver, I ascertained that ten 
grsdns of phosphorus required for their conversion into phosphoroiu 
acid, such as exists in the hydrat just descnbcd, 7,7 grains of oxf- 
gene ; and it is evident from this result, compared with that on the 
combustion of phosphorus, in which phosphoric acid is formed, dnt 
the quantity of phosphorus being the same, it requires twice as 
much oxygene to become phosphoric acid, as it requires to form 
phosphorous acid ; and from these data, the number representiDg' 
phosphorus, must be regarded as about 20, and phosphorous acid 
will consist of 20 phosphorus, and 15 oxygenc, or 35 ; and phospho- 
ric acid of 20 phosphorus and 30 oxygene, or 50. 

That the hydro-phosphorous acid is a compound of phosphorusi 
oxygene, and water, is shewn by heating it in contact with ammonia 
over mercury ; the ammonia unites to the pure acid, and water is ex- 
pelled. I find by experiments on the quantity of water it affords, 
thut it consists of four proportions of phosphorous acid, and two of 
water. 

I have made no experiments on the proportion of oxygene in the 
red oxide. It possibly will be found to consist of two proportions of 
phosphorus, and one of oxygene. 

5. Phosphorus and chlorine combine with great facility when 
broiij^ht in contact with each other at common temperatures; and 
compounds may be formed from their union, containing different pro- 
ns of the two elements. 




C 165 ] 

When chlorine is introduced into a receiver exhausted of air, and 
containing phosphorus, the phosphorus takes fire and bums with a 
pale flame throwing off sparks, and a white substance rises and con- 
denses on the sides of the retort. 

If the chlorine be in considerable quantity, as much as twelve 
cubical inches to a grain of phosphorus, the phosphorus will entire- 
ly disappear, and nothing but the white powder will be formed ; and 
about 9 cubical inches of the chlorine will be found to be absorbed ; 
and no new gaseous matter will be produced. 

The powder is a compound of phosphorus and chlorine. I first 
described it as a peculiar body in 1810, and various analytical and 
synthetical experiments which I have made, prove that it is com- 
posed of about 1 of phosphoi*us and 6.8 of chlorine in weight. 

Its properties are very peculiar. It is a snow white substance. 
It is very volatile, and rises in a gaseous form at a temperature much 
below that of boiling water ; under pressure it may be fused, and 
then it crystallizes in prisms which are transparent. 

It acts violently upon water, which it decomposes. Its phospho- 
rus combines with the oxygene, producing phosphoric acid, and its 
chlorine with hydrogene forms muriatic acid. 

It produces flame when exposed to a lighted taper; and wheii 
passed through a glass tube heated red, with oxygene, is decompo- 
sed f the oxygene forms phosphoric acid with the phosphorus, and 
the chlorine is disengaged. Dry litmus paper exposed to its vapour 
|n a vessel exhausted of air is reddened. It combines with ammonia 
when it is introduced into a vessel containing it, with much heat ; 
and they form together a compound insoluble in water, indecom- 
posable by acid or alkaline solutions, and having characters analo- 
gous to an earth. 

It is evident from the analysis, that it consists of two proportions 
of chlorine, supposing the number representing chlorine, 67, or of 
four, supposing it 33.5, 134 to one of phosphorus 20, and the num- 
ber representing it is 154. It is analogous to an acid in many of its 
properties. According to the principles of nomenclature which I 
|;iaye ventured to propose, its name will be fihos/i/iorana, 

6. I have already referred to the substance produced by passing 
phosphorus through corrosive sublimate. It is a fluid as clear as 



[ 166 ] 

water; its specific gpravity is to that of water as 1.45 to 1. It may 
be called fihoafihorane. I first obtained it in a pure forniy in 1809. 
It appears from the circumstances already detailed, that it condsts 
of one proportion of phosphorus 20, and one of chlorine 67, and the 
number representing it is 87*. It emits acid fumes when exposed 
to air, decomposing the vapour in the air, and if made to moisten 
paper, it is converted into acid in the air, without any inflammatioD. 
It docs not redden dry litmus paper plunged into it ; the vapour from 
it bums in the Hame of a candle ; its action upon water has been al- 
ready referred to. When it is introduced into a vessel containing 
chlorine, it is converted into phosphorana : if made to act upon am- 
monia, phosphorus is produced, and the same compound as that fisrm- 
ed by phosphorana and ammonia. 

7. When phosphorus is gently heated in phophorane, a part of it 
dissolves, and the fluid, when exposed to the air, gives off acid fumes 
from its action upon its vapour it contains, and a thin film of phospho- 
rus is left behind, which usually inflames by the heat generated from 
the decomposition of the vapour. The first compound of thb kind 
was obtained by M. M. Gay Lussac and Thenard, by distilling phos- 
phorus and calomel together in 1808, and they imagined it to bet 
peculiar combination of phosphorus, oxygene, and muriatic add. 

No experiments have been as yet made to determine the quanutf 
of phosphorus which phosphorane will dissolve ; probably a definite 
combination may be obtained, in which the proportions of chlorine 
will correspond to the proportions of oxygene in the oxide of phos- 
phorus. 

8. An elastic fluid, which has the peculiar property of inflaming in 
contact with the atmosphere, may be procured by heating together 
slacked lime, or strong solution of potassa or soda, and phosphorus. 
It is expedient to deprive the air contained in the vessel in which it 
is generated of oxygene, by burning phosphorus or a taper in it ; 
the gas should be preserved over mercury ; it soon becomes adulte« 
rated by exposure to water containing air. 

This gas differs in properties according to the manner in which it 
is made ; I have obtained it from phosphorus and alkaline lixivia of 

* 136 grains of it decomposed by nitrate of silver, alTorded 43 grains of boip- 
tilver, and 100 grains of silver absorb 32.5 of chlorine to become homsilvec. 



[ 167 ] 

Specific gravities varying from 4 to 7, 1 being the standard of hydros 
gene : its smell is very disagreeable : water absorbs about -^ of its 
Tolume of the gas. It detonates when brought in contact with chlorine^ 
producing a brilliant green light ; but the results of the detonation 
have never been minutely examined. It explodes with a most 
intense white light in oxygene gas ; the heaviest spontaneously in- 
flammable gas that I have ever made, absorbed rather less than an 
equal volume of oxygene. 

When electrical sparks are passed through gasses of this kind 
for a long time, a reddish film which burns like phosphorus is depo- 
sited ; ususally there is no change of volume^ and the remaining gas 
is hydrogene. When a gas, the specific gravity of which was 6^ 
was heated for some time over mercury in contact with zinc filings, 
there was an expansion of volume to more than | ; a substance was 
formed superficially on the zinc, which had the characters of a com- 
pound of phosphorus and zinc. There wns an expansion when fine- 
ly divided platina was heated in a portion of the same gas. Potas- 
sium in excess made to act upon it by a spirit lamp produced a ra- 
pid increase of its volume ; 2 parts became rather more than 3. 
The potassium was affected as it would have been by a union with 
phosphorus, and the g^s was found to be pure hydrogene. 

This substance, which was discovered by M. Gengembre in 1783, 
has been called fihosfihoretted hydrogene, 

9. When solid hydrat of phosphorous acid is heated in a retort 
6ut of the contact of air, solid phosphoric acid is formed, and a large 
quantity of elastic fluid is generated, which has very peculiar pro- 
perties; I discovered it at the same time as the solid hydrat of phos- 
phorous acid, namely, in February 1812. This gas has a disagree- 
bie smell, but not nearly so fetid as that of phosphoretted hydro- 
gene: it does not explode spontaneously, but detonates violently 
when heated in contact with oxygene to about 300° Fahrenheit. It 
explodes in chlorine with a white flame. Water absorbs \ of its 
volume of this gas. In an experiment in which a small quantity on- 
ly was weighed, its specific gravity appeared to be to ilial of hydro- 
gene as about 12 to I. 

When potassium is heated in it, its volume is doubled, and the 
gas produced is pnre hydrogene. When sulphur is sublimed in one 



[ I6B ] 

■ volume of it, a sulphuret bf phosphorus is foraied^i anil nearly 2 
volumes of sulphuj-etted hydrogtne produced. When detonated 
with oxygEDC in escesSi tiiree in volume of it absorb more than five 
in volume of oxysene, and a little phosphorus is always thrown 
down ; when 8 of it in volume arc dctonat'd liy an electrical spark 
with 2 of oxygenc, there is h coneiderablc deposition of phosphorus, 
antl 9 of gas, which has the odour of common phosphoreucd hy- 
dvogene, remain ; one volume of it absorbed nearly four volumes of 
slilonne. 

I venture to propose the name of hydro[thogfihorU gas for this elas- 
tic iluid. Il appears to be composed of 1 proportion of phosphorus 
and 4 ofhydrogenc, two volumes of hydrogene being compressed in 
the space of one, and the number representing it is 34. 

It is probable that the gas called phosphuretted hydrogene some* 
times contains tills gas, mixed witli common hydrogene, and pet;- 
haps a [iscuUar elaalic fluid, consisting of one proportion of phos- 
phorus, and two of hydrogene, which has the property of spontane- 
ous inflammation. Hydrophosplioric gas I find does not become spon- 
taneously explosii'c by mixture with hydi'ogene. 

There is not, perhaps, in the whole series of chemical pheno- 
mena a more beautiful illustration of the theory of definite propor- 
tions, than that offered in the decomposiiion of hydrophosphopoui 
acid into phosphoi-ic acid and hydi-ophosphoric gas. 

Four proportions of the acid contain four proportions of phospho- 
rus, anil four of oxygene ; two proportions of water contain four 
proportions of hydrogene, and two of osygene. The six proportions 
of osygene unite to three proportions of phosphorus to form three 
of phosphoric acid, and the four proportions of hydrogene combine 
with one of phosphorus to form one proportion of liydrophosphoric 
gas ; and there alt no other products. 

10. Phosphorus and sulphur are capaljle of combining ; they may 
be united by fusing them together in a tube exhausted of air, or 
under water; but in the last case they must be used only in small 
quantities ; as at the moment of their action water is decomposed, 
sometimes with explosions. This compound, wiiicli has been called 
■ulphuret of phosphorus, was described by Margraaf in 1762, He 
.' See la below. 



C i6i> 3 

formed it of equal parts of the two subsunces, hut phosphorus and 
sulphur may be united into one mass in a variety of proportions; and 
these mixtures are more fusible than either of their constituents. 
The most fusible compound I have found, is that formed by the two 
bodies united in tlie proportion of one and a half of sulphur, to two 
of phosphorus. Tliis remains liquid at 40^ of Falirenheit ; and would 
appear to be composed of one proportion of sulphur 30, and two of 
phosphorus 40. When solid its colour is yellowisli-wbitc. It is 
more combustible than phosphorus, and rises undccomposcd by a 
strong heat. 

The p>oints of fusion and evaporation of phosphorus and sulphur, 
are so near each other, that it is not easy to asceitain the diifeiTiKc 
between true chemical combinations of these Ixxlies in different pro* 
portions, and mixtures of the chemical compounds, with the 1)odics 
themselves; 8 parts of phosphorus in wuij^hi united to one of sul- 
phur, remain fluid at 68** of Fahrenheit ; and one of phosphorus with 
3 of sulphur, congeal at about 100°. 

1 1 . When phosphorus is fused and exposed to the action of the 
Voltaic spark, taken by means of platina wires, phosphurctted hy- 
drogenc in small quantities is produced fixjni it ; but there are no 
proofs that hydrogene is essential to its existence ; and phosphorus 
in its common state, may contain a minute portion of the hydruret of 
phosphorus mixed with it ; it would be very difficult to detect in 
phosphoric acid, the small quantity of water that this hydrogcni' 
would produce ; and the red colour which phosphonis sometimes 
possesses, seems to be owing to an admixture of small quantities of 
oxide of phosphorus. There are some analogies that favour the idea 
of the compound nature of phosphorus, which will be discussed in 
the progress of this work ; but in the arrangements of tlie facts of 
the science^ it must be sull regarded as an undecompounded body. 

12. Phosphorus has not as yet been applied to any of the purposes 
of the common arts ; but various preparations of it are employed for 
producing quick inflammation. One of the best, is a sulphuret of 
phosphorus, containing two of phosphorus to one of sulphur ; a little 
of it applied to a common brimstone mutch, inflames when gently 
rubbed. 



[ 170 ] 

V. Of Carbon or Charcoal^ and the Diamond. 

1 . The name carbon, signifies the pure inflammable part of char- 
coal) lamp-black, and other similar substances. The purest knovD 
form in wliich it can be obtained, is by passing oils or spirits of wine 
through ignited tubes. It then appears as an impalpable black pow- 
der ; it has no taste nor smell ; it is a conductor of electricity ; it 
is miore than twice as heavy as water. For tlie common purposes 
of experiments, the charcoal of light wood, such as the alder, that 
has been exposed to boiling water, and afterwards ignited to whit^ 
ness, is sufficiently pure. Such charcoal, however, rapidly attracts 
moisture from the atmosphere, so as to increase in weight from 13 
to 14 per cent., and when -dry, absorbs several times its volume of 
any gas to which it may be exposed, and it must therefore be em- 
ployed immediately after ignition, and whilst yet warm. 

Carbon, whether coherent in charcoal, or in powder, is infusible 
by any heat that has hitherto been applied. I have exposed it to the 
powers of intense ignition of different Voltaic batteries ; that of Mr. 
Children, mentioned page 84, one of 40 double plates of 1 8 inches 
square, and the battery of 2CX)0 double plates of 4 inches, both in 
vacuo, and in compressed gasses, on which it had no power of che- 
mical action. A litUe hydrogene was given off from it, and it slowly 
volatilized in these experiments, and the part remaining was much 
harder than before, so as in one case to scratch glass, and the lustre 
was greater ; but its other properties were unaltered, and there was 
no appearance of fusion. Its capacity for heat, according to Dr. 
Crawford, is to that of water as .2631 to 1. 

2. There arc two distinct combinations of carbon and oxygenC} 
which have been referred to, page 58. 

Carbonic acid is formed whenever charcoal or carbonaceous mat- 
ter is burnt in air or oxygenc, and it is evolved during fermenta- 
tion, by the decomposition of animal or vegetable substances, and 
from limestones by ignition, or the action of acids. 

The most expeditious mode of procuring it for chemical purposes 
MJIJL the action of weak solution of muriatic acid on powdered mar- 

1 



i' 



i 



C 171 ] 

blc. It may be collected over water, or, for accurate experiments, 
over mercury. 

Carbonic acid gas was the first elastic fluid certainly distinguished 
from air ; the knowledge of its acid nature is owing to Dr. Black, 
who discovered it in 1755. Mr. Lavoisier, nearly 30 years after- 
wards, ascertained its composition. 

Carbonic acid gas extinguishes flame, has a peculiar sharp taste, 
and a faint but agreeable smell. It is not I'espirable. Its specific 
gravity is to that of hydrogene as 20.7 to 1 . 100 cubical inches weigh 
at the mean temperature and pressure, 47 grains. 

Carbonic acid gas is absorbed by water, which unites to its own 
volume of the gas at 41°. By heat it is expelled from the water. 

If carbonic acid gas be poured from one vessel into another ves- 
sel containing a lighted taper, the flame is exunguished.^i 

It reddens litmus paper, and combines with alkalies, alkaline 
earths, and metallic oxides. 

A synthetical proof of the composition of carbonic acid gas, has 
been already given, page 58. 

Common charcoal, even when very well burnt, contains a little 
hydrogene, and aflbrds a minute quantity of water in its combustion; 
but the charcoal from the decomposition of oil gives carbonic acid 
gas alone. It bums when inflamed m dry oxygene with brilliant 
scintillations ; there is no percepuble change in the volume of the 
gas ; and when the process is complete, the oxygene is found con- 
verted into carbonic acid gas. 

The proportions of the elements in carbonic acid gas are easily 
learnt by the difference between its weight and that of oxygene. 
This difference proves, as has been stated before, that it must con- 
sist of 13 of charcoal to 34 of oxygene. 

The constitution pf carbonic acid gas is proved analytically by its 
action upon potassium. If this metal is strongly heated in a retort 
containing the gas, it takes fire, and bums with a red light. Char- 
coal in fine powder is deposited, the gas disappears, and oxygene is 
found added to the potassium. 

3. The compound of carbon and oxygene, containing less oxygene 
than carbonic acid gas, may be formed in many modes besides that 
rlcscribed in page 58; as by igniting chalk or any substance con^- 



\ 




C 1-2 J 

uiiJi^ carbonic acid with charccaL iron, or tin ; or by igmting ^Jfi- 
cultlv reducible metallic oxices with charcoal, or by passing caii)ft- 
nic acid gas over charcoal heated co whiteness, in a porcefatin tiibe. 
In this last case, the composition of the gas is shewn by the circBm- 
stances of the experiment, charcoal disappears, and the carlxmic acid 
becomes carbonic oxide gajs, and there is a consideraUe expansion. 
The true nature of this elastic fluid was discovered by Mr. Cmik- 
shank in March, 1801. 

Carbonic oxide may be puriied from the carbonic acid xrith which 
it is usually mixed, by washing in lime water. 

It is combustible, and by the contact of an inflamed or igmted 
body, bums in the atmosphere with a lambent blue flame. Its spe- 
ciflc gravity, according to Cruikshank, is to that of hydrogene is 
13.2 to I. 100 cubical inches weigh about 30 grains. 

Carbonic oxide may be taken into the lungs, but is fatal to ammal 
life. I once took three inspirauons of it mixed with about ^ of com- 
mon air ; the effect was a temporary loss cf sensation, which wis 
succeeded by giddiness, sickness, acute pains in different parts of 
the body, and extreme debility ; some days elapsed before I entirelf 
recovered. 

Water absorbs about -J^ of Its bulk of carbonic oxide. 

Chlorine has no immediate action on carbonic oxide, when they 
are exposed to each other in common day -light over dry mercury ; 
r.ot even when the electric ^lark is passed through them. M. M. 
Gay Lussac, Thenard. and Murray, have asserted that they do not 
act on each other even when long exposed to the direct solar beams. 
But experiments which I have seen made by my brother, Mr. John 
Davy, prove the contrary ; they rapidly combine under this circum- 
stance, and ^vhen in equal volumes, are condensed to one-half; ind 
form a peculiar gas, which he has discovered is possessed of verv 
curious properties, approaching to an acid in its nature. 

The- niiture of carbonic oxide, and the proportions of its elements, 
ai-c easily demonstrated by analytical experiments. When two in 
voluaic of it are mixed \vith one in volume of oxygene, and an elec- 
ti ic'-i s-ark passed through the mixture, an inflammation takes place, 
I'v'j in vclume of pure carbonic acid are formed, and thei-e is no 



t 173 3 

When potassium is strongly heated in it, combustion take^ place, 
charcoal is deposited, no gas is disengaged, and ozygene is added to 
the potassium. 

From the experiments on carbonic acid and carbonic oxide, i: is 
evident that the numl^er representing carbon is about 11. 4; and car- 
bonic acid is represented by 30 added to 1 1.4, or 41.4; and carbonic 
oxide by 1 5 added to 1 1 .4, or by 26.4. 

Some chemists have been perplexed to find a reason why carbonic 
oxide, which contains more carbon, is lighter than carlx>rJc acid ; 
but, as Mr. Dalton has ingeniously and justly observed, there is no 
difficulty in this circumstance ; carbon in the gaseous state, is proba- 
bly considerably lighter than oxygene. The specific gravity of gas- 
ses bears no relation to the density of the fluids or solids, from which 
they arc formed ; ether is lighter than water ; but the vapour rising 
from it is much heavier than steam. If carbonic oxide be supposed 
to be constituted by equal volumes of gaseous carbon and oxygene, 
occupying the space of two in volume, then the specific gravity of 
gaseous carbon will be to that of oxygene as 13 to 17; or if the con- 
stitution of the carbonic oxide is similar to that of the nitrous oxide, 
it will be only as 6.5 to 1 7. 

4. No compound of carbon and chlorine has been as yet discover- 
ed. They have no action on each other under any circumstances to 
which they have been exposed. 

5. There are two compounds of carbon and hydrogcnc, which arc 
perfectly distinct and well characterized bodies. 

One of them, which has been called carburetted hydrogene^i^ dis- 
engaged in certun natural operations, particularly during the decom- 
position of vegetable substances ; it is the gas evolved in stagnant 
waters. It may be procured by the distillation of coal that bums with 
flame, and by decomposing the salt called acetite of potash by a red 
heat ; it should be washed with lime water to separate it from car- 
bonic acid. 

It bums with a bright yellowish flame. It has no taste, but a dis- 
agreeable empyreumatic smell. Water absorbs about -^^ of its vo- 
lume. Its specific gravity, in its purest form, is to that of hydrogcnc 
as rather less than 8 to 1. 100 cubical inches weip:ht abo\it 17 t»rains. 




[ 174 3 

When one of this gas hi volume is mixed with two of oxyg^ 
gas, and an electrical spark passed tlirough tliem over mercury ; 
water and about one in volume of carbonic acid are the products. 
Hence one in volume of carburetted hydrogenc must contain two 
in volume of hydrogene gas, and as much carbon as will form a vo- 
lume of carbonic acid. This likewise is shewn by the phaenomeoa 
of its electrization. When points of platina are electrically ignited 
in it, or sparks passed through it, charcoal is deposited, and double 
its volume of hydrogcne is produced. When it is mixed with twice 
its volume of chlorine over mercury, and acted on by the electrical 
spark, an inflammation takes place, charcoal is deposited, there is a 
considerable expansion, and about four volumes of muriatic acid gas 
are produced. 

It is evident from these different results that carburetted hydro- 
gene may be considered as composed of one proportion of carbon 
1 1 .4, and four of hydrogene 4, and the number representing it will 
be 15.4. 

6. When a mixture of four parts of oil of vitriol and one part of 
strong spirits of wine, or alcohol, is heated in a retort, a gas is gene- 
rated, which, when washed by water, is found to be a peculiar gase- 
ous compound of carbon and hydrogene ; it has been called olefiant 
^asy and likewise aufier carburetted hydrogene. It bums, when 
kindled, with a beautiful white flame of intense splendour. Accord- 
mg to Dalton, water absorbs j- of its volume of the gas. Its specific 
gravity is to that of hydrogene nearly as 13 to 1; 100 cubical inches 
of it weigh between 29 and 30 grains. 

When it is mixed with an equal volume of chlorine, the two gas- 
scs condense each other, and a peculiar fluid is formed, which has 
been supposed to be an oil ; but which is a peculiar comfioundy not 
soluble in water, and composed of hydrogene, carbon, and chlorine. 
The nature of olefiant gas may be easily demonstrated, and likewise 
the proportion of its elements. If pure sulphur be sublimed in the 
gas in a glass tube over mercury, there is a great expansion ; sulphu- 
retted hydrogene is formed, and charcoal deposited ; one volume of 
gas forms about two in volume of sulphuretted hydrogene : the sul- 
phur must not be used in much larger quantity than is sufficient to 
Mni^^ the hydrogene ; for in this case, by the long application of 




C 175 3 

heat, the volume is more than doubled ; two grains of sulphur and a 
cubical inch of gas are proper proportions. 

The gas is decomposed by electrical sparks ; one volume of it ex- 
pands to about two ; charcoal is deposited, and the expanded gas is 
found to be hydrogene. 

It detonates with great violence by the electrical spark, when mix- 
ed with three times its volume of oxygene ; water and nearly two vo« 
lumes of carbonic acid arc formed in this process. 

When it is detonated with an equal volume of oxygene, it expands 
greatly, and the two gasses together become more than tliree volumes 
smd a half. In this case only the •} or -^ of a volume of carbonic 
acid gas is formed, but more than a volume and a half of carbonic 
oxide ; a little hydrogene is consumed, but the greatest part remains 
untouched and mixed with the carbonic oxide ; and it may be sepa- 
rated by combustion with chlorine. 

If an experiment of this kind could be' made without the produc- 
■ tion of any carbonic acid, or the consumption of any hydrogene, the 
Tolumc of the gasses would be exactly doubled, and they would con- 
sist of equal parts of carbonic oxide and hydrogene. 

It is evident from all these experiments, that olefiant gas may be 
considered as constituted by two proportions of carbon 22.8 and 4, of 
hydrogene 4, and the number representing it is 26.8 : and supposing 
a double volume of gasiidUs carbon in oleRant gas, its specific gra- 
vity will be found to be the same as from the data presented by car- 
bonic oxide. 

7. Most of the gasses that form carbonic acid in burning were no- 
Jticed by Dr. Priestley, who confounded them under the general 
name of heavy inflammable air. Olefiant gas was first described as 
a specific substance, in 1794, by Bondt, Dciman, and a society of 
Dutch chemists. Mr. Bcrthollet and Mr. Murray suppose that 
there is a great variety of gasses which consist of oxygene, hydro- 
gene, and carbon, in different proportions ; but the experiments of 
Mr. Dalton, Dr. Henry, and Dr. Thomson, are entirely opposed to 
these views ; and the researches which I have made in conjunction 
with my brother, Mr. John Davy, have convinced me of tJie correct- 
ness of Dr. Henry's opinion, that what have been called different 
oxicarburctted hydrogene gadses are merely mixtures of olefiant gas^ 



[ 176 ] 

-cai'bUi'Cttcd liydrogcnc, carbonic oxide, and hydrogcnc gasses. We 
used chlorine for separating olefiant gas at common temiperatureS) 
and the same substance for separating hydrogene by explosion, or 
the action of light ; and sulphur for decomposing the carburetted 
hydrogene : and in these modes of analysis our results were unequi- 
vocal. 

8. Carbon and azote have no known action on each other. 

9. I have already referred to the alcohol of sulphur. This sub- 
stance was supposed by M. M. Clement and Desormes to be a com- 
pound of carbon and sulphur ; there can be no doubt, from what has 
been stated, that this idea of its composition is incorrect : I have 
found it, however, sometimes to contain a minute quantity of cha^ 
coal ; and there may possibly be a triple compound of carbon, sul- 
phur, and hydrogene. Sulphur is very soluble in oils and other 
compounds which consist principally of hydrogene and carbon. The 
charcoal used for making the alcohol of sulphur always produces 
sulphureous acid by burning, though previously exposed to a strong 
red heat, and affords sulphur to a strong solution of alkali ; but the 
quantity is very minute, and it may be questioned whether the sul- 
phur is not in combination with the earthy or alkaline matter the 
charcoal contains ; and no certain definite compound of sulphur and 
carbon can be as yet admitted in the arrangements of the science. 

10. Phosphorus has been supposed capable of uniting to carbon; 
but in cases when specimens of phosphorus afford charcoal it is most 
probably mixed with the substance, or in triple combination with 
oxygene and hydrogene ; and no distinct action of the two bodieS) 
and no definite compound of them has as yet been described. 

1 1. A number of fonms of carlwn arc found in nature ; one of the 
most interesting of them is the diamond; the properties of this stone 
are well known, i^ is the hai'dest of the gems, and is usually crystal- 
lized, often in the form of a six-sided prism terminated by a ax- 
sided pyramid : its specific gravity is about 3.5 ; it does not conduct 
electricity. Of all known bodies it has the greatest power of re- 
fracting light. When the diamond is strongly heated in air, it con- 
sumes away ; and if it be exposed to oxygene continuously ignited 
by a burning glass, or by other means, it acts upon the oxygene 

:ly in the same manner as charcoal. The volume of the oxygene 



[ 177 ] 

is not perceptibly changed, and it is found converted into carbonic 
acid. M. Lavoisier first determined that carbonic acid was formed 
from diamond ; and Messrs. Tennant, Allen, and Pepys, have de- 
monstrated by some reflncd experiments, that it produces about the 
same quantity a& an equal weight of chai'coal. Hence it has been 
concluded, that the diamond is pure carbon, differing from charcoal 
merely in the arrangement of its paits. When it is considered, how- 
ever, that charcoal is a conductor and diamond a nonconductor of 
electricity, and that their physical properties diiTer entirely, it is im- 
possible to receive this conclusion without doubt. I found that dia- 
mond powder heated strongly with potassium became blackened ; 
and an effect was produced on the metal similar to that which the 
absorption of a minute quantity of oxygene would occasion ; tliis 
would lead to the suspicion that there may be a little oxygene in 
diamond ; but new experiments are wanting to prove this, and the 
quantity, if any, must be very minute, which does not harmonise 
with the doctrine of definite proportions. If it should be ultimately 
fbiind that the diamond is merely pure carbon, it will be an argu- 
ment in favour of the varieties of elementary forms being produced 
by different aggregations or arrangements of particles of the same 
matter ; for it is scarcely possible to fix upon bodies less analogous 
Uian lamp black, and the most perfect and beautiful of the gems. 

12. Plumbago or black lead, and antliracite or stone coal, are both 
tolerably pure fonns of the carbonaceous element. In plumbago the 
carbon is united either chemically or mechanically to about ^ of 
iron ; in anthracite with small quantities of earthy matter. In the 
anthracite of Kilkenny in Iieland, tlie texture is often fibrous, and 
the substance has all the characters of well-burned charcoal. In 
flaming coal the carbonaceous element is united to bitumen. 

13. Few substances are more important in civilized life than the 
ilifTerent forais of carbon ; in their vanous uses they are essential to*' 
the comforts and well being of society, and are necessary in almost 
all the useful arts and manufactures. 

The inflammable gasses procured by the distillation of pit-coal* 
have already been successfully used in manufactories for the purpose* 
of affording light, and the application is at once safe and oecono- 
Tniral. 

7. 



C 178 ] 

In nature the carbonaceous element is constantly active in an im- 
portant series of operations ; it is evolved in fermentation and com- 
bustion, in carbonic acid ; it is separated from oxygene in the organs 
of plants, is a principal element in animal structures, and is found 
in different forms in almost all the products of organized beings. 

VI. Of Boron* ^ or the Boracic basis. 

1 . There is a white crystalline substance found native in volcanic 
districts called boracic acid. It may be procured artificially from 
borax by heating it in oil of vitriol diluted with eight times its weight 
of water : it is difficultly soluble in water, and may be separated by 
a filtre of cloth or paper. When this substance, slightly moistened^ 
is exposed between two surfaces of platina, electrified by a Voltaic 
batteiyof not less than 100 dorble plates, a dark-coloured substance 
separates on the plate negatively electrified. This substance is fe- 
ron^ or the basis of the boi*acic acid. In this way it can be procured 
only in veiy minute quantities, and to obtain it for the purposes of 
experiment, boracic acid that has been long exposed to a red heat, 
is powdered and strongly ignited with an equal weight of potassiam, 
ill a tube of iron or copper. The result is exposed to diluted mu- 
riatic acid, and washed with it till notliing remains but a dark pow- 
der, which, when dried at a red heat, is the substance in question. 

2. I first procured boron in October, 1807, by the electrical de- 
composition of boracic acid, and by potassium in March,- 1808; but 
not in sufficient quantities to examine its properties, or to ascertain 
its nature. IVI. M. Gay Lussac and Thenard, in June, 1808, made 
the experiment of heating boracic acid and potassium together, but 
they did not describe the propeilies of boron till the middle of No- 

• In my first paper on this substance I named it boracium, for I supposed that 
in hs pure form it would be found to be metallic ; subsequent experiments have 
not justified this conjecture. It is more analogous to carbon than to any other 
substarce ; and I venture t</ propose Boron as a more unexceptionable name ; the 
termination in um having been long used as characteristic of a metal. M. M. 
Ga;.' Lussac and fhenard have proposed to call it Bore, a word that cannqt with 
proj)riety be adopted in our language, though short and appropriate in the French 
nomenclature. 



C 179 } 

vexnber ; and in the beginuing of the same month 1 had procurcti 
sufficient quantities of the substance to ascertain its chemical rela- 
tions. M. M. Gay Lussac and ThcnaixU 1 believe, recomposcd the 
boracic acid before me, and our exporimcnts were indeiKMidcnt of 
each other ; but in my first paper on [)otassium and sodium, read at 
the Royal Society, in November, 1 807, at a time when the rrcncli 
chemists had no idea of tlie existence of the alkaline metals, I point- 
ed out the probable application of these bodies to the decomiX)sition 
of the acids not decompounded. 

3. Boron is an opaque, dark olive-coloured powder, infusible, and 
not volatile at any temperature to wiiich it has as yet been ex|)osed. 
When heated strongly in contact with air, it burns, and forms dry 
boracic acid. In oxygene gas, it throws oif bright scintillations, be- 
comes coated with boracic acid, and the portion not convened into 
acid is found darker coloured than before. When gently heated hi 
chlorine, it emits white fumes, but has no energetic action on the 
gas. It is a nonconductor of electricity, and insoluble in water. 

4. That boron combines with oxygene is shewn by tlie phxnome* 
na of its combustion. Boracic acid is the only well-known result of 
their combination : the preparation of boron proves that the bomcic 
acid consists of this body united to oxygene, for oxygene is added to 
the potassium in the process. It is very difficult to ascertain the 
proportions of boron and oxygene in boracic acid, for the lioracic ucld 
formed in combustion prevents the process from going tm ; anrl tlic 
black substance, which is probably an oxide of iKiron, is burnt only 
with great difficulty. From comparing the quantity of potassium 
required to decompose a given quantity of boracic acid, with the 
quantity of oxygene absorbed in the production of the acid, I am in- 
clined to believe that U^racic acid cannot contain much less than ^ 
of its weight of oxygene : I have made a number of experiments on 
this subject, but have never gained perfectly satisfa/:tory results. 
M. M. Gay Lussac and Thenard conceive that l>oracic acid cxtutsxiu^ 
only -I of its weight of oxygene ; but their conclusions were drawn 
from the action of boron on solution of nitric acid, and the cva{K/ra- 
tion of the products; and bf>racic acid forms volatile com[)/>undH 
both with water and nitric acid ; for f find that dry nitre and lx>rar.i/ 
acid afford- Sy distillation-, a fluid containing a considerable r^uanfiu 



C 180 ] 

of boracic acid. From the quantity of ammonia required to neutra- 
lize boracic acid, it appears that the number representing it is about 
160; and to destroy the alkaline properties of 90 parts of potassa 
requires twice 1 60 of boracic acid, so that its acid powers are ex- 
tremely feeble. 

Boracic acid, in its common form, is in combination with water ; 
it then appears as a series of thin white hexagonal scales ; its taste 
is very slightly acid ; it reddens vegetable blues. By a long conti- 
nued white heat the water is driven off from it, and a part of ihc 
acid sublimes; the reraidning acid is a transparent fixed glass, which 
rapidly attracts moisture from the air. The compound of boracic 
acid and water appears to contain, from my experiments, about 57 
parts of acid to 43 of water. The specific gravity of the hydrat of 
boracic acid, as it may be called, is 1.479^ that of the dry acid 
1.803. 

Boracic acid is very little soluble in water ; even when boiling, 
that fluid does not take up -^^^ of its weight. It dissolves in alcohol, 
and gives it the power of burning with a green flame. 

5. Much still remains to be known respecting the nature and pro- 
perties of boron, and its combinations. Probably a combination of it 
with chlorine may be formed. It seems to exert no action on any 
of the inflammable bodies except sulphur, which dissolves a little of 
it by a long-continued heat, and gives a green tint. 

It has hitherto been obtained in quantities too smajl to ascertain 
whether it will have ^ny applications to the arts. 



C 181 ] 



DIVISION V. 

OF METALS; THEIR PRIMARY COMBINATIOI^S WITH OTHER 
. UNDECOMPOUNDED BODIES, AND WITH EACH OTHER. 

1. General Observations. 

1 . 1 HE metals form a numerous and most important class of na- 
tural bodies ; they are connected with each other by close analogies, 
and by remote analogies to the inflammable solids described in the 
'.preceding pages : the number of metals known, or the existence of 
which may be presumed, amounts to 38. The chai^acteristic pro- 
perties of the metals are a high degree of lustre, opacity, combusti- 
bility, and the power of conducting electricity. A considerable de- 
gree of specific gravity was formerly considered as an essential 
character of metallic substances; but I have discovered bodies 
lighter even than water, which agree in all other essential qualities 
with metals, and which consequently must be arranged with them. 
In the order of classification to be adopted in the following pages, 
the most inflammable metals will be the first considered : though of 
recent discovery, they are the most important as agents of analytical 
chemistry, and have offered the means of reducing other substances 
to the metallic form. The most inflammable metals produce alka- 
lies, alkaline earths, and earths in combustion. Other metals aflbrd 
the substances called oxides, which are analogous to earths ; and a 
few are converted into acids. The metals that produce alkalies are 
potassium and sodium ;. the alkaline earths are formed from metals, 
which have been called barium, strontium, calcium, and magnesium. 
The metals supposed to be contained in common eartlis are sili- 
cium, alumium, zircoiuum, ittrium, and glucium. The metals that 
produce oxides are manganese, zmc, tin, iron, lead, antimony, bis- 



C 182 ] 

muth, tellurium, cobalt, copper, nickel, uranium, osmium, tungsten, 
titanium, columbium, cerium, palladium, iridium, rhodium, mercuryi 
silver, gold, and platina. The metals that produce acids are arsenic, 
molybdenum, and chromium. 

2. The metals differ considerably in their mechanical properties, in 
degrees of hardness, ductility, and tenacity ; all of them that are 
fusible by common means assume regular crystalline forms by slow 
cooling, and these forms are usually cubical or octoedral. The 
common metals, in consequence of their fusibility, malleability, hard- 
ness, and durability, have been the most important instrument of the 
arts ; the uses of them have been essential to the prog^ss of civili- 
zation ; and most of the comforts, and many of the luxuries and re- 
ilnements of social life are connected with their applications. 

2. Of Potassium, 

• 

i . There is a body usually called potash or the vegetable alkali, 

which may be thus procured : quick lime is mixed with soludon of 
wood ashes, and boiled for some time with it. The liquor so obtain- 
ed, after being passed through bibulous paper, is evaporated till i 
solid matter remsdns ; this solid matter is heated with alcohol or 
pure spirit; the spirit is separated by distillation in a vessel of 
silver; a fusible solid mass is produced, which is the substance in 
question. 

To form fiotasaium^ this substance in a thin piece, is placed be- 
tween two discs of platina connected with the extremities of a 
Voltaic apparatus of 200 double plates; it will soon undergo fusion, 
oxygene will separate at the positive surface, and small metallic 
globules will appear at the negative surface, which consist of potas- 
sium. I discovered this metal in the beginning of October, 1807. 

?. It may be procured by chemical means without electricity. If 
iron turnings be heated to whiteness in a curved gun-barrel, and 
potash be melted and made slowly to come in contact with the turn- 
ings, air being excluded*, potassium will be formed, and may be 
collected in a cool part of the tube ; this method of procuring it was 
'^^hnrered by M. M. Gay Lussac and Thenard, in 1808. It may 

-1 ■"""'"" 



C 183 3 

likewise be produced by i^ung potash with charcoal^ as M. Curau- 
dau shewed in the same year. 

3. Potassium is possessed of very extraordinary properties ; it is 
lighter than water, its specific gravity is between 8 and 9, water 
being 10. It is a solid at common temperatures; it is very soft, and 
easily moulded by the fingers. It fuses at about 150<> Fahrenheity 
and rises in vapour, in a heat a little below that of redness. It is 
perfectly opaque. Its colour is white, like that of silver when it is 
newly cut, but it rapidly tarnishes in the air ; and to be preserved 
from change must be kept under naphtha. It is a conductor of 
electricity. When thrown upon water it acts with great violence, 
swims upon the surface, and bums with a beautiful light, which is 
white mixed with red and violet; the water in which it bums is 
found alkaline, and contains a solution of potassa. It inflames when 
gently heated in the air, burns with a red light, and throws off fumes, 
which are alkaline. It burns spontaneously in chlorine with intense 
brilliancy. 

It acts upon all fluid bodies containing water, or much oxyg^ne, 
or chlorine ; and in its general powers of chemical combination may 
be compared to the alkahest, or universal solvent imagined by the 
alchemists. 

4. Potassium combines with oxygcne in dificrent proportions. 
When potassium is gently heated in common air or in oxygene, the 
result of its combustion is an orange-coloured fusible substance; 
and for every grain of potassium consumed, about a cubical inch 
and -^ of oxygene disappear. To make the experiment accurately 
the metal should be burnt in a tray of platina covered with a coating 
of the salt called, in the French nomenclature, muriate of potash, a 
substance immediately to be described, which may be easily done 
by fusing it in contact with the platina. This salt is one of the few 
substances that has no action on potassium or its oxides. 

The substance procured by the combustion of potassium at a low 
temperature, I had observed in October, 1807, but I supposed it to 
be the oxide of potassium containing the smallest quantity of oxy- 
gene, for it eflfcrvesced in water; M. M. Gay Lussac and Thenard, 
in 1810, first demonstrated its re^ nature, and shewed that it W8» 



[ 184 ] 

the combination of oxygene and potassium containing the largest 
quantity of oxygene. 

The gas produced by its effervescence with water is oxygene. 
When it is fused and brought in contact with combustible bodiesj 
they bum with vividness. When it is heated in carbonic acid, oxy- 
gene gas is expelled, and it is converted into the compound called' 
subcarbonate of potash. 

When it is heated very strongly upon platina, oxygene gas is ex- 
pelled from it, and there remains a difficultly fusible substance of a 
gray colour, vitreous in its fracture, and which dissolves in water 
without effervescence, but with much heat, and renders the water 
alkaline. This substance is pure potash or fiotassa, which was im-v 
known in its uncombined state till I discovered potassium, but wluch 
has long been familiar to chemists combined with water in the sub- 
stance which has been called pure potash; but which ought . to be^ 
called the hydrat of fiotaaaa. 

That the potash obtained by alcohol in the manner described id 
the beginning of this section is a compound of potassa and water,- is 
shewn by many expenments. If it be made to act upon iron turn- 
ings at a dull red heat, the iron becomes combined with oxygene, 
hydrogene is given off in abundance, and the alkali loses its easy 
fusibility, becomes harder, more opaque, and of greater specific 
gravity. In producing potassium in the experiment of acting upon 
white hot iron turnings by common potash, hydrogene is disengaged 
in abundance from the decomposition of the water in the potash; and 
I have procured this water by heating together the potash prepared 
by alcohol and boracic acid; 100 parts of potash treated in this way 
gave between 1 7 and 1 8 parts of pure water. 

Potassa entirely free from water may be procured by other nieans 
besides the decomposition of the orange oxide of potassium, or the 
action of iron on common potash : for instance, by acting on potas- 
sium by a small quantity of water, or by heating potassium with 
common potash. The proportion of oxygene in potassa is learned 
by the action of potassium upon water : 8 grains of potassium pro- 
rom water about 9 cubical inches and a half of hydrogene ; and 
there must be added to the metal four cubical inches and 
ricrs of oxyti-eiic. 




[ 185 J 

5. It has l>een mentioned, page 64, that the number representing 
l)Otassium is 75 : and it appears from the experiments that the orange 
oxide of potassium must consist of 1 proportion of potassium 75, and 
3 of oxygene 45; and the number representing it is 120. Potassa 
must consist of one proportion 75, and one of oxygene 15, and the 
number representing it is 90. Hydrat of potassa, or the potash pre- 
pared by alcohol, must contain one proportion of potassa 90, and one 
of water 17*. 

6. When i)otassium is heated strongly in a small quantity of com- 
mon air, the oxygene of which is not sufRcient for its conversion into 
potassa, a substance is formed of a grayish colour, which, when 
thrown into water, effervesces without inflaming. This substance is 
likewise generated in experiments on the production of potassium 
by ii*on and hydrate of potassa, when a little common air is admitted 
into the barrel. It is doubtful whether it be a mixture of potassa 
and potassium, or a combination of potassium with a smaller quanti* 
ty of oxygene than exists in potassa, that is, a protoxide of potassium. 
If a protoxide of potassium, it probably contains two proportions of 
potassium and one of oxygene, 

7. I have already referred to the action of potassium and chlorine ; 
the mfiammation produced when thin pieces of potassium arc intro- 
duced into chlorine is very vivid : potassium separates chlorine from 
hydrogene and phosphorus with inflammation ; and when potassiuni 
is miade to act upon sulphurane there is a violent explosion. The 
attraction of chlorine for potassium is much stronger than the attrac- 
tion of oxygene ; potassa, and the orange oxide of jjotassium, are im- 
mediately decomposed by chlorine, the chlorine combines with the 
metal, and the oxygene is set free. 

The combination of chlorine and potassium is the substance which 
has been improperly called muiiate of potash, and which, in common 

* In the few experimentB that I have made on hydrat of potassa, there has been 
rather more water mdicated, between 17 and 19 per cent.; but the potash I used 
was, I doubt not, adulterated with a little «oda, as no particular care was taken to 
purify it, and hydrat of soda contains more water in proportion : and there is great 
reason to believe that 90 and 17 are the true estimation. M. M. Gay Lussac and 
Thenard allow about ^ of water in potash. 

2 A 




[ 186 J 

cases, is formed by causing muriatic acid and solution of potassa to 
act upon each other, and by iieating the mixture to redness ; in which 
cuse the hydrcjjene of the acid, and the oxygene of the alkali are set 
free as water; and tlie nictal of the alkali and the chlorine of the acid 
combine. From various analytical experiments it appears that mu- 
rii-.to of potash, which may be called /fj^aftmne^ consists of 75 of po- 
tassium and 67 of chlorine, and the number reprcscnthig it is 140. 
Potassane is the only known combii^.ation of potassium and chlorine. 

8. There appears to be a gaseous combination of potassium and 
hydrogeiie ; for I found that when potassium is heated strongly in 
hydrogciic the gas contracts in volume, and becomes spontaneously 
inflammable, and gives alkaline fumes in its combustion. M. Si 
Gay Lussac and Thenard state that there is a solid compound d 
hydrogene and potassium, which may be obtained by heating the 
metal for a long while in the gas, at a tempemtin'C just below that 
of ignition. They describe it as a grayish solid, and state that it 
^ives off its hydrogene by the action of mercury. As yet no experi- 
ments have been made on the proportions in which hydrogene and 
potassium combine. 

9. Potassium and sulphur combine with great energy when they 
are heated together, producing much light and heat, even when the 
experiment is made out of the contact of air. The sulfihuret qf/io- 
tGssium is of a dark gray colour; ac;s with great energy upon water, 
producing sulphuretted hydrogene, and burns brilliantly when heat- 
ed in the air,fcecoming the salt called sulphate of potash. From my 
experiments there is every reason to believe that this compound con- 
sists of one proportion of sulphur 30, and one of potassium 75, and 
the number representing it will be 105. Potassium has so strong 
an attraction for sulphur that it rapidly separates it from hydrogene; 
and potassium heated in sulphuretted hydrogene takes fire and bums 
with great brilliancy, and sulphuret of potassium is formed, and hy- 
drogene set free. 

10. Potassium and phosphorus enter into union producing light: 
hut they act o:i ,' ach other with less energy than potassium and sul- 
phur. The fihosji/turct of fiotassium in its common form is a sub- 

of a dark chocolate colour ; but when heated with potassium 
%t excess it becomes of a deep gray colour, and of considerable 




L 1^" J 

iustrc, so thai it h llkeiy li.^: ;;..'.-:.!.•.: lib ;.n.i poiissiuni are capable 
of combir.i;!^ in two pixTM-::io:.s ; tjjo1;/'»';. the ci.ucoh.tw-colc"". ...d 
substance coiituI::h one j^!opor::(. h tA t-u- .;. r.i.cl the L::i'k j^ra sub- 
stance two propMiioi.i oi i!;f- nil.;..]. 
— ^ The j>hohpi,urLt o{' j^ot;x:>.'siuin ii.iiji v. itli :-rc:it briilic^ncy when 
expo:»ed to air, :.nd v. Iici: t!i;o'.\n i:.:«j v..:- v p. ot.uc' s ;.ii explcsioi. 'n 
consequence of tin- iniuicdii.tc disLi..^ ;..;tiiiti.i of pho^phui cited hy- 
drogcne. 

1 1. When riuircoal is picsciii du/ii.c; tlic production of potassium, 
it usually contains a snudl (luiriiity of carljcnitceous niaitcr; and char- 
coal tliat has been he'-itd stroiv^Iy in contact with potassium effer- 
vesces in water, aiid rei.derr* it alkaliiiC, though previously exposed 
to a temperature at which potashiuui ri-^esin vapour. These circum- 
stances shew iliat tlicre la an attraction, thoujjli feeble, between po- 
tassium and carbon ; but as yet no conipcAUid of the two bodies of 
which the proponlons can be abr^ii;ncd bus been obtained. 

12. Potasoium like otlier metals has resisted all attempts to re- 
solve it into other forms of matter. Since I first discovered it, and 
announced it as an undecompoundc:d substance, there has been much 
discussion respectin.ij its nature. ^I. M. Gay Lussac, Thcnaixl, Hit- 
ter, and Dalton, supposed that it v/as a compound of hydrogcne and 
potassa; but the first two chemists have allowed that the phaenonic- 
na .arc incompatible with such an hypothesis; in this case potassium 
shoidd iorni hydrat of potassa, or substaiiccs containing water in 
combustion, which is not the case ; nor has hydrogcne been in any 
instance obtained in experiments on potassium except when sub* 
stances known to contain hydrogene were present ; and it would not 
be more absurd to say that phosphorus is a compound of hydrogene 
and phosphoric acid, than to say that potassiimi is a compound of hy- 
drogcne and potassa. 

13. Potassium, of all known substances, is that which lias the 
strongest attraction for oxygene ; and it produces such a condensa- 
tion of it that the oxides of potassium are heavier than the metal 
itself. Potassium may be used as a general agent for detectuig the 
presence of oxygene in bodies ; and a number of substances unde- 
composable by other chemical agents are readily decomposed by 
this substance. 




C 188 ] 

The compounds of potassium are of great use in the arts ; potassa 
enters into the composition of soft soap, and tlic salts having a basb 
of potassa are many of them used in medicine. 

S. Sodium. 

1. Sodium may be procured exactly in the same manner as potas- 
sium, by electiical or chemical decomposition, the mineral alkali^or 
die alkali from the ashes of marine plants being used instead of peari 
ashes. Rather a higher degree of heat is necessary for its produc- 
tion by the action of iron. 

I discovered sodium a few days after I discovered potassium, iu 
the year 1807. 

2. In many of its characters it resembles potassium ; it is as white 
as silver, has great lustre, and is a conductor of electricity. It enten 
into fusion at about 200° Fahrenheit, and rises in vapour at a strong 
red heat. Its specific gravity is between 9 and 10. . When heated 
strongly in oxygene or chlorine, it burns with great brilliancy. When 
thrown upon water it effervesces violently, but does not inflame, 
Mvims on the surface, gradually diminishes with great agitation, and 
renders the water a solution of soda. It acts upon most substances 
in a manlier similar to potassium, but with less energy. It tarnishes 
in the air, but more slowly, and like potassium it is best preserved 
under naphtha. 

3. Sodium forms two distinct definite combuiations with oxygene: 
one is pure soda, which has long been known, combined with water, 
in the substance which has been called by chemists Soda^ but which 
was not examined in its uncombined state, till I formed it from the 
metal ; the other is the orange oxide of sodium, which I observed 
in 1807 ; but of which the true nature was pointed out in 1810 by 
M. M. Gay Lussac and Thenard. 

Pure soda may be made by buniing sodium in a quantity of dr 
contahiing no more oxygene than is sufficient for its conversion into 
the ulkali, i. e. the metal must be in excess : a strong degree of 
heat must be applied. 

Pure soda is of a gray colour, it is a nonconductor of electricity, 
f»f a •^hus fracture? and re(iuirin«»; a strong red heat for its fusion. 




[ 189 3 

When a little water is added to it, there is a violent action betwcl-i^ 
the two bodies ; the soda becomes white, ciystailine in its appcai'- 
ance, and much more fusible and vob.tile, and is then the substance 
which has been long known under the name of soda, but wliich may. 
with more propriety, be called hydrat of soda. 

The oxide oj" sodium may be formed by burning sodium in oxy- 
gene gas in excess. It is of a deep orange colour, very fusible, and 
a non-conductor Oi' electricity ; when acted upon by water, it gives 
off oxygene gas, and the water becomes a solution of soda ; it defla- 
grates when strongly heated witli combustible bodies. 

The proportions of oxygene in soda, and the orange oxide or per- 
oxide of sodium, are easily learnt by the action of sodium on water, 
and on oxygene. If a given weight of sodium, in a little glass tube, 
be thrown, by means of the finger, under a graduated inverted jar 
filled with water, the quantity of hydrogene evolved will indicate the 
quantity of oxygene combined with the metal, to form soda ; and 
when sodium is burnt slowly in a tray of platina, lined witli dry 
common salt in oxygene in great excess ; from the quantity of oxy- 
gene absorbed, the composition of the peroxide may be learnt. From 
experiments that I have made on this subject, compared with those 
made by M. M. Gay Lussac and Thenard, it appears that the num- 
ber representing sodium is 88, and that soda consists of one propor- 
tion of sodium, and two of oxygene, 88 and 30 : the oxide of sodium, 
of one proportion of sodium, and 3 of oxygene, 88 and 45 : and hy- 
drate of soda (soda prepared by alcohol) contains one proportion of 
sodium, two of oxygene, and two of water, and the number represent- 
ing it is 152. 

When sodium is kept for some time in a small quantity of moist 
air, or when sodium in excess is heated with hydrat of soda, a dark 
grayish substance is formed, more inflammable than sodium, and 
which affords hydrogene by its action upon water. It is probable 
that this is sodium in its first degree of oxygenation, or the /irotoxidr 
of sodium ; but as yet no experiments have been made on its consti' 
tution. If the protoxide, it is likely that it consists of one propor- 
tion of sodium, and one of oxygene. 

4. Only one combination of sodium and chlorine is known: it is 
liie important substance cofn?finn nat*. Tt m.n* he foiTncd directly 




C 190 ] 

by combustion, or by decomposing any compound of chlorine by so* 
clium. Its properties are well known ; it is a non-conductor of elec- 
tricity, is fusible at a strong red heat, is volatile at a white heat, and 
crystallizes in cubes. Sodium has a much stronger attraction for 
chlorine than oxygene ; and soda or hydrate of soda is decomposed 
by chlorine, oxygene being expelled from the first, and oxygene and 
water from the second. 

Potassium has a stronger attraction for chlorind than sodium has; 
and one mode of procuring sodium easily, is by heating together to 
redness common salt and potassium. The compound of sodium and 
chlorine has been called muriate of soda, in the French nomenclsf 
ture ; for it was falsely supposed to be composed of muriatic acid 
gas, and soda ; and it is a curious circumstance, that the progressof 
discovery should have shewn tliat it is a less compounded body than 
hydrate of soda, which six years ago was considered as a simple sub- 
stance, and one of its elements. According to the nomenclature 
which I have ventured to propose, the chemical name for commA 
salt will be sodane. 

Common salt consists of one pi*oportion of sodium, 88, and two of 
clilorinc, 134; and the number representing it is 222: when tliepro* 
per corrections are made, the most accurate analyses, pailicularly 
those of Dr. Marcet, are found to agree with this number. 

3. There is no known action between sodium and hydrogcne, of 
azote. 

6. Sodium combines readily with sulphur, and with phosphorus, 
presenting similar phsenomena to those presented by potassium. The 
sulphurcis and phosphurets of sodium agree in their general proper% 
ties with those of potassium, except that they are rather less inflam- 
mable. They form by burning, compounds of sulphuric and phos- 
phoric acid and soda, and therefore must contain two proportions ot 
the hiflammable substances, to one of sodium. 

7. Sodium, when made from substances containing charcoal, 
usually aflbrils charcoal by combustion ; but as yet no definite com- 
bination of the two bodies has been obtained. No experiments hs^t 

.driH^ieen made on the action of sodium on boron. 

^8. Potassium and sodium combine with great facility, and fom 
puliar compounds, which differ in their properties according to the. 



/ 

J 



[ 191 ] 

proportions of their ingredients. By a small quantity of sodium, po- 
tassium is rendered fluid at common temperatures, and its specific 
gravity considerably diminished. Eight parts of potassium, and one 
of sodium, form a compound that swims in naphtha, and that is fluid 
at the common temperature of the air. Three parts of sodium, and 
one of potassium, make a compound, flui'l at common temperatures. 
A little potassium destroys the ductility of sodium, and renders it 
very brittle, and very soft. 

9. The compounds of sodium are of great importance in the com- 
mon arts, and are subservient to many of the wants of life. Soda 
is the most important ingredient in the different species of glass, and 
in hard soaps. The glasses are composed of soda united to earths 
and oxides; the soaps consist of soda, united .to oily substances. 
Common salt is found abundantly in nature ; it exists in small 
quantities in almost all ivaters and all soils. It diminishes the ten- 
dency of animal or vegetable substances to decompose, and probably 
preserves the ocean in a state fitted for the purposes of animal life. 
It is a part of the nourishment of animals, and though taken in very 
small quantities, seems to perform an important part in their oeco- 
nomy. 

10. The compounds formed by potassium and sodium, like the me- 
dals themselves, are possessed of strong resemblances ; they may how- 
ever be chemically distinguished by a very simple test ; the diluted 
aqueous solutions of the compounds of potassium, remler cloudy the 
nitro-muriatic solution of platina, which is not the case with similar 
soludons of the comix>unds of sodium. Most of the compoimds of 
.sodium differ from those of potassium, in containing double propor- 
tions of the other elements. Potassa contains one proportion of oxy- 
gene only; soda contains two, and the salts having potassa for their 
basis, contain only one proportion of acid, whilst those having soda 
for their basis, contain two. The attractions of potassium for all 
substances that have been examined, are stronger than those of 
sodium; and when sodium is procured from compounds, by the 
agency of potassium, 150 parts in weight of potassium, or two pro- 
portions, are required to produce 88 parts of sodium, or one pro- 
portion. 




t 192 j 



3. h 



artum. 



1. There is a mineral substance found in Cumberiand, Yorkshire^ 
and other parts of Britain, called Witherite, or carbonate of baiyti. 
By dissolving tliis substance in dilute solution of nitric acid, evapont- 
ing the solution to dryness, and heating the salt obtained to whitenesS) 
a light fawn-coloured powder is procured, which is baryta or barium 
combined with oxygene. To obtain barium^ a quantity of this sub-" 
stance is made into a paste, with water, and placed on a plate of 
platina ; a cavity is made in the paste to receive a globule fl 
mercury; the mercury is rendered negative, the platina positive, bf 
means of a Voltaic battery, containing about 100 double plates. 

In a short time an amalgam will be formed, consisting of mercuiy 
and barium. This amalgam must be introduced into a little tubft 
made of glass free from lead, which must be bent in the form off 
retort, filled with the vapour of naphtlia, and hermetically sealed. 
Heat must be applied to the end of the tube containing the amalgam, 
till all the mercury has been driven oflf; there will remain a soBd 
difficultly fusible metal, which is barium. 

2. I first gained indications of the decomposition of baryta, in the 
end of October 1 807, and I obtained an alloy of it with iron, in 
March 1808. The process of electrifying mercury, in contact vitb 
the cartli, was pointed out to me in the course of my enquiries, by 
M. M. Berzelius and Pontin of Stockholm, in May 1808 ; and in the 
beginning of June in the same year, I obtained the metal, 

3. Barium, as procured by heating the amalgam, appeared of a 
dark gray colour, with a lustre inferior to that of cast iron. It was 
considerably heavier than sulphuric acid, for though surrounded by 
globules of gas, it sunk immediately in that fluid. It instantly be- 
came covered with a crust of baryta, when exposed to air, and burnt 
with a deep red light, when gently heated. When thrown into 
water it cflervesced violently, disappeared, and the water was found 
to be a solution of baryta. 

Barium as yet has been obtained only in very minute quantities^. 
T have never possessed enough of it to ascertain its generld chemical 



re 



^ 



[ 193 ] 

and physical characters, and no experiments upon it have been 
published by any other person. 

4. From some results that I have obtained, it seems probable that 
barium may be procured by chemical, as well as electrical decom- 
position. When baryta, or the salt improperly called muriate of 
baryta, ignited to whiteness, was exposed to the agency of potassium, 
that metal being sent through it in vapour, a dark gray substance 
appeared, diffused through the baryta, or the muriate, not volatile, 
that effervesces copiously in water, and that lost its metallic appear- 
ance by exposure to air : — the potassium in this process was con- 
verted into potassa. 

5. The only well known combination of barium, with oxygene, is 
baryta or baria. It is of a pale grayish green colour. Its specific 
gravity is about 4, that of water being 1 . This substance is a non- 
conductor of electricity, has a strong caustic taste, reddens turmeric, 
and renders green, vegetable blues. When acted upon by a small 
quantity of water, it heats violently, becomes white, unites to a pro- 
portion of water, and becomes a hydrate. The pure alkaline earth 
is infusible, except by an intense heat; the hydrate fuses at a strong 
red heat; a considerable part of its water is expelled by a still 
higher temperature. Baryta is soluble at 60**, in about 20 parts of 
water, and at 212° in about 2 parts. That baryta is composed of 
barium and oxygene, is proved by the combustion of barium in oxy- 
gene ; in which, as I have found, oxygene is absorbed, and no pro- 
duct but baryta formed. It is likewise proved synthetically by the 
action of barium upon water, in which case hydrogcne is evolved ; 
and analytically it appears from the action of potassium on the earth. 
From indirect experiments, I am inclined to consider bar3rta as com- 
posed of 89.7 of barium, and 10.3 of oxygene : and supposing the 
earth to consist of one proportion of metal and one of oxygene, the 
number representing barium will be 1 30, and that representhig the 
alkaline earth will be 145. 

Barium, as would appear from the experiments of M. M. Gay 
Lussac and Thenard, is capable of combining with more oxygene 
than exists in baryta. These able chemists state, that when baryta 
is gently heated by a spirit lamp, in a glass tube filled with oxygene 
gas, an absorption of the gas takes place. As yet no experiments 

2 B 



[ 194 3 

have been made on the properties of this oxide of barium^ or on the 
quantity of oxygene it contains : probably baryta may be easily com- 
bined with oxygene, by heating it with hyper-oxynmriate of baryta. 
The hydrat of baryta^ if its composition be estimated from M. Ber- 
thollet's experiments, consists of one proportion of baryta and one of 
water. 

6. One combination only of bai'ium and chlorine is known : it majr 
be formed by heating bar3^a in muriatic acid gas, or in chlorine. 
In the first case, the oxygene of the baryta produces water by com- 
bining with the hydrogene of the acid ; in the second it is expelled: 
and in an experiment made on purpose, I found that for every part 
in volume of chlorine absorbed, half a part of oxygene was given off 
from the alkaline earth. Hence it may be concluded that the com- 
pound of barium and chlorine contains one proportion of metal 130 
and one of chlorine 67. This substance is fusible by a very strong 
heat, is very soluble in water ; its taste is bitter, its colour white, it 
is crystalline and transparent. It is improperly called in the French 
nomenclature, muriate of baryta. According to the principles of 
nomenclature which I have proposed, its name will be barane, 

8. No other combinations of barium, except those with oxygene 
and chlorine, have been as yet examined ; there can, however, be 
little doubt that its powers of combination will be, in many respects, 
analogous to those of potassium and sodium, as of all metallic sub- 
stances, it is the nearest related to these bodies. 

9. The compounds of barium have as yet been applied to the arts 
in very few cases. Baryta is employed in small quantities, in the 
manufacture of certain kinds of porcelain ; most of the salts contain- 
ing baryta as a basis, are poisonous. The combination of baryta and 
carbonic acid, made artificially by pouring a solution of carbonate of 
ammonia, into a solution of nitrate of baryta, forms a pigment of a 
very pure white colour. 

4. StrGniium. 

I. Strontium may be procured precisely in the same maimer as 
barium ; carbonate of strontia, or strontianite, a mineral found at 
Strontian in Scotland, being used instead of witheritc. I first pro- 



[ 195 ] 

cured this metal in 1808, but in quantities too small to make an accu- 
I'ate examination of its properties. It seemed very analogous to ba- 
rium, had not a very high lustre, appeared fixed, difficultly fusible, 
and not volatile. It became converted into strontia by exposure to 
air, and >vhen thrown into watef, decomposed it with great violence, 
producing hydrogene gas, and making the water a solution of 
strontia. 

2. One combination of sti'ontium with oxygene only is at present 
known ; it is strontia^ or strontites, the substance procured by burn- 
ing strontium. It may be pixxiuced in large quantities by igniting 
strontianite intensely with charcoal powder, or by heating to white- 
ness the salt formed from this fossile, by the action of nitric acid. 
It appears of a light fawn colour, and agrees, in many of its charac- 
ters, with baryta. It is fusible only by an intense heat. Its specific 
gravity is between three and four, water being one. It is soluble in 
about 200 parts of water, at common temperatures, and is much 
more soluble in hot tlian cold water ; its taste is acrid and alkaline, 
it reddens paper tinged with turmeric. When acted upon by a 
small quantity of water, it becomes hot, its colour changes to 
white, and it is converted into a hydrate, and then becomes fusible 
at a white heat. From indirect experiments, I am disposed to re- 
gard it as composed of about 86 of strontium and 14 oxygene ; and 
supposing it to contain one proportion of metal and one of oxygene, 
the number representing strontium will be 90, and that representing 
the earth 105. 

3. No experiments have as yet been made on the direct combina- 
tion of strontium and chlorine : but a substance which appears to 
c<»isist of these two bodies, and no other elements, may be made, 
by heating strontia strongly in chlorine, or muriatic acid gas, or by 
ignitmg to whiteness the salt formed by the solution of strontianite 
in muriatic acid. By the action of chlorine on strontia, oxygene is 
expelled : by the action of muriatic acid gas upon it, water is form- 
ed. The com.pound of chlorine and strontium, or atrontancy is a 
-white substance, difficultly fusible, fixed in the fire, a non-conductor 
of electricity, and of a peculiar bitter taste ; when brought in con- 
tact with the flame of wax, tallow, oil, or alcohol, it tinges it of a 
jose colour ; and tiiis is a distinctive character of the compoimds of 



[ i96 J 

strontium ; the salts formed from it give this tint to flame, those o£ 
baiyta give a yellow tint. From direct experiments I ascert^ned 
tiiat 50 parts of strontanc consisted of about 29 parts of metal and 
2 1 of chloiine ; so that it must be regarded as composed of one pro- 
portion of strontium, and one of gas, 90 and 67. 

4. No experiments have as yet been made on the action of stron- 
tium on any of the other elementary substances. 

5. None of the compounds of this body have as yet been apptied 
to any of the purposes of the arts, and its combinations are rare in 
nature. 

5, Calcium, 

1 . Calcium may be obtauied by the same processes as barium and 
strontium. Mild calcareous earthy or chalk, being used instead of 
"witherite and strontianite ; or common well-burnt lime may be cm- 
ployed for making the paste, from which the mercurial amalgam ii 
to be formed by Voltaic electricity. 

I first procured calcium about the same time as barium and stroo^ 
tium, but only in very minute quantities, so that little can be said 
conceiving its nature. It appeared brighter and whiter than these 
two metals, and burnt, when gently heated, producing dry lime. I 
have had no opportunity of examining its general physical and che- 
mical qualities* 

2. There is only one known combination of calcium and oxygene, 
which is the impoitant substance, lime or calcia. The nature of this 
substance is proved by the phaenomena of the combustion of calci- 
um ; the metal becomes converted into the cai*th, with the absorp- 
tion of oxygene gas. When the amalgam of calcium is thrown into 
water, hydrogene gas is disengaged, and the water becomes a solu- 
tion of lime ; and from the quantity of hydrogene gas disengaged, 
compared with the quantity of lime formed in experiments of this 
kind, M. Berzelius has endeavoured to asceitain the proportion of 
oxygene in lime. The nature of lime may be also proved by ana- 
lysis ; when potassium in vapour is sent through the earth, ignited 
ta-^ffcjcss, tlie potassium, I have found, becomes potassa, and a 
i ^^stance of metallic splendour, which is calcium either 




C 19V ] 

wholly or partly deprived of oxyg^ne, is found embedded in the po* 
tassa, and it effervesces violently, and forms a solution of lime, by 
the action of water. 

Lime is obtained for common purposes, from marble of the whitest 
kind, such as the Parian or Carara marble, by long exposure to a 
strong heat. .It is a white soft substance, of specific gravity 2.3. It 
requires a intense degree of heat for its fusion, and has not yet been 
rendered volatile. Its taste is analogous to, but milder than that 
of barjrta and strontia. It is soluble in about 450 parts of water, and 
seems to be nearly. as soluble in cold, as in hot water. It acts up* 
on vegetable colours in a manner similar to the other alkaline 
earths. When water, in snudl quantities, is added to it, a consider- 
able heat is produced, a portion of the water combines with the lime, 
and it becomes a hydrate ; but water does not adhere to it with the 
same degree of energy, as to baria and strontia, for it may be ex- 
pelled by a strong red heat. From the experiments of M. Berzelius, 
and those which I have made, it appears that lime consists of about 
30 of metal to 7.5 of oxygene, and the number representing calcium 
is 40, and that representing lime 55 ; and the hydrate of lime must 
cfmsist of 55 lime and 17 water, which estimation agrees with the 
experiments of M. Lavoisier and Mr. Dalton. 

I have attempted to combine lime witli more oxygene, but with* 
out success. 

. 3. When lime is heated strongly in contact with chlorine, oxy- 
gene is expelled, and chlorine absorbed ; and, as happens in all tlie 
decompositions of metallic oxides, of which the metals combine with 
only one propoition of oxygene and chlorine for every two in volume 
of chlorine absorbed, a volume of oxygene is expelled. The sub- 
stance formed by the action of chlorine on lime, as the oxygene of 
the lime is expelled, must evidently consist of chlorine and calcium. 
It has been called dry muriate of lime ; according to the true view 
of its composition, it may be called calcane. It is a scmi-transpa-> 
rent crystalline substance, fusible at a strong red heat, a non-con- 
ductor of electricity, has a very bitter taste, rapidly absorbs water 
from the atmosphere, and is extremely soluble in water ; by the 
evaporation of its solution at a low heat, crystals may be obtained, 
which consist of calcane, combined with more than a third tl»eir 



[ 198 ] 

weight of water. Trom my experiments, it appears that calcanfe 
consists of 31 chlorine and 19 of calcium, and hence it may be sup- 
posed to contain one proportion of the metal, and one of the g^, and 
the number representing it on this idea is 107; and it is evident) 
from the experiment on the action of chlorine on lime, that the pro- 
portion of oxygene in lime, and of chlorine in calcium, must be in 
the ratio of 15 to 67. 

4. As yet no experiments have been made on the combinatioDi 
of calcium with any of the inflammable, or acidiferous substances, 
or metals. 

5. The compounds of calcium are found abundantly on the sun 
face of the globe, and are of great importance in the oeconomy of 
nature, and in the processes of art. Lime combined with caibonic 
acid is an essential part of fertile lands : a number of rocks are 
constituted by this substance. Gypsum or alabaster, is lime com- 
bined with sulphuric acid ; and the earth of bones consists of lime 
united to phosphoric acid. There is no animal or vegetable sab- 
stance that does not contain larger or smaller quantities of calcare- 
ous matter. The uses of lime in mortar are well known. Quick- 
lime, employed as a manure, tends to decompose and dissolve inert 
vegetable matter, and renders it proper for the nourishment of 
plants ; and in this operation the lime is united to carbonic acid, and 
becomes a permanent part of the soil. In the process of tanning', I 
lime is employed to remove the hair from the skins of animals, and 

it is used in certain operations of bleaching, dyeing, and other use- 
ful arts. 



6. Magnesimn. 

1. Magnesium* may be procured from the earth called magnesia, 
which is the same as the calcined magnesia of druggists, by proces- 
ses similar to those referred to in the three preceding sections ; but 

• In my first paper on the decomposition of the earths, published in 1808, I 
called the metal from magnesia, magnium, fearing lest, if called magnesium, it 
should be confounded wiih the name formerly applied to manganese. The candid 
18 of some philosophical friends have induced me to apply the terminatidR 
manner. 




C 199 3 

u nhich longer time is required to produce an amalgam of magne- 
sium and quicksilver, by electrical powers^ than to produce amal- 
gams of the metals of the otlier alkaline earths. 

I succeeded in decomposing magnesia likewise, in the following 
manner: I passed potassium in vapour through magnesia, heated to 
intense whiteness, in a tube of platinum, out of the contact of air; 
I then introduced a small quantity of mercury, and heated it gently 
for some time in the tube. An amalgam was obtained, which by dis- 
tillation, out of the contact of the atmosphere, afforded a dark gray 
metallic film, which was infusible at the point at which plate glass 
softened, and which, in the process of distillation of the mercury, ren- 
dered the glass black at its point of contact with it. This film burnt 
when heated strongly, with a red light, and became converted into a 
nrhite powder, which had the character of magnesia : when a por- 
tion of the metal was tlirown into water, it sunk to the bottom, and 
effervesced slowly, becoming covered with a white powder ; by 
adding a little muriatic acid to the water, the effervescence was vio- 
lent ; the metal rapidly disappeared) and the solution was found to 
contain magnesia. 

I have made several experiments with the hope of obtainmg 
larger quantities of magnesium, such as might have enabled mc to 
examine its chemical and physical properties ; but without success. 
It is very difficult to procure a pure amalgam of magnesium by po- 
tassium and mercury ; the heat must be intense ; and at a high tem- 
perature, potassium acts with great energy upon platina, so tliat un- 
less the tube is very solid, it is destroyed in the process, and when 
the heat is not very great, potassium remains in tlie tube, which is 
found afterwards in the amalgam. The potassium may however be 
separated by the action of water ; which, even in the amalgam, ra- 
pidly converts it into potassa, but which has a much feebler action 
on magnesium. When the amalgam contains potassium, it like- 
wise usually contains platinum, which is ver>' soluble in the com- 
pound of potassium and quicksilver. 

2. There is only one known compound of magnesium and oxy- 
gene, which is the substance from which the metal is procured, 
Magnesia, That magnesia consists of magnesium and oxygcnc, is 
proved both by analysis and synthesis. In the production of mag- 



/ 



[ 200 ] 

r^esinm by potassium, the poiassium is found coDrerted into polasaa, 
find therefore must have K^^d oxygene from the magnesia ; and in 
the formation of m&gnesiiL from magnesium, oxy^ne is absorbed. Ko 
experiments have as yet been made to determine the proporuoDs cf 
the elements in mag;nesia; but from experiments vhich I hai-ennde 
on tlie combinations of this substance with acid&. assuming that tbej 
aic single propordons^ I am inclined to adopt 53 as the Dumber r^ 
presenting it ; and if it be supposed to be constituted by one pro* 
porJon of metal, and one of oxygene^ the number representing the 
metal will be SS. 

Magnesia appears in its common form, as a white soft powder; 
its specific gravity is between '2 and 3. It is found in nature in tk 
cnstalline form ; specimens have been brought from North Amen- 
ca, which nearly resemble talc in their external characters. Mag- 
nesia has scurcelv anv taste, no smell; it reddens turmeric. It is 
infusible, except by the intense heat produced by the combustian of 
hydrogenc gas in oxygene, or that genertied by Voltaic electricity. 
It is scarcely soluble in water, but produces heat when water is 
mixed with it, and it absorbs a considerable portion of the fluid. 
When it is procured by the decomposition of a solution in which it 
is combined with an acid, by means of solution of potassa or soda, 
it falls do^vn in -union with water, as a hvdrat ; but the water ad- 
heres to it with a very feeble attraction only, and Is expelled entire- 
ly at a red heat. Hydrat '^f mafsntua^ when dried at 212*, appears 
in coherent semitransparent masses, very brittle and soft; it contains 
about \ of its weight of water. 

3. When magnesia is strongly heated in contact with chlorinC) 
chlorine is absorbed, and oxygene expelled, and in the usaal propor- 
tions as to volume. Hence it is evident that there exists a combi- 
nation of magnesium and chlorine ; though this body, which may be 
':&lled magnetanr^ has never been examined in a separate state. The 
salt c?.lled muriate of magnesia, is a compound of magnesane and 
water, and when it is acted en by a strong red heat, by far the great- 
^part of the clilorine unites to the hydrogene of the water, and 
in the form of muriatic acid gas, and the oxygene or the decom- 
watcr combines v.ith the magnesium to fonn magnesia; some 



/ 




[ 201 ] 

HMgnesaoe u, however, found mixed with the mag^csiii) which 
nffords crystals of muriate of magnesia by the action of water. 

4. No experiments have as yet been made on the action of mag- 
neaium upon any of the inflammable or metallic substances. 

5. The compounds of magnesium occur extensively diffused in 
nature. Magnesia exists in certain limestones which arc found in 
difTerent parts of Great Britain and Ireland, and which are less fitted 
fi>r the general purposes of manure than common limestone. Mag- 
nesia, in its uncombined state, as appears from the experiments of 
Mr. Tennant, is injurious to plants, but united to carbonic acid, it 
leems to form an useful part of the soil : the magnesian limestones 
axe diftinguished by their slow solution in acids; and they render 
weak soluticms of nitric acid turbid by their action upon them. Mag* 
ntaia, and some of its saline combinations, are used in medicine ; its 
ItppUcation in bleaching has been referred to in an early part of this 
Work. 

7. Muminum. 

1. When a solution of ammonia or of potassa, not in excess^ is 
thrown into a solution of alum, a substance falls down, which when 
well washed, and dried at a red heat, is alumina. This substance 
appears to contain a peculiar metal, but as yet aluminum has (not 
been obtained in. a perfectly free state, though alloys of it with other 
metalline substances have been procured sufficiently distinct to indi- 
cate the probable nature of alumina. Alumina cannot be decompos- 
ed by the electrization of mercury in contact with it, in the same 
Bianner at the alkaline earths. The first experiment by which I 
obtained evidences of its composition, was made in 1808, by fusing 
iron negatively electrified in contact with it ; the earth was moist in 
this procesS) and a very high Voltaic power was applied. The glo- 
bule of metal obtained was whiter than pure iron ; effervesced slowly 
in water, becoming covered with a white powder, and the solution in 
muriatic acid decomposed by an alkali, afforded alumina and oxide of 

iron. 

By passing potassium in vapour, through alumina heated to white- 
nessy the greatest part of the potassium became converted into po- 

2 c 



[ 202 ] 

^u»a, which formed a coherent mass with that part of the alunuDi 
not decompounded, and in this mass there were numerous gray pi^ 
Ucles, having the metallic lustre, and which became white whai 
heated in the air, and which slowly effervesced in water. In a case 
in which a similar experiment was made, a strong red heat only be- 
ing applied to the alumina, a mass was obtained, which took fire 
spontaneous' ly by exposure to air, and which effervesced violently m 
water, anct which probably contained the basis of alumina united to 
potassium. 

2. That oxygene exists in alumina, cannot be doubted, when the 
conversion of potassium into potassa by its action upon it, is cons- 
dered ; and that it contains an inflammable substance united to oxy- 
gene, seems likewise e\ident; and that this is metalline in its naton 
appears extremely likely, both from the facts detailed, and from 
analogy ; but this point cannot as yet be considered as demonstrated. 

Alumina, in the form in which it is usually obtained, has no taste 
nor smell, adheres strongly to the tongue, has no action upon vege- 
table colours, is insoluble in water, is soluble in all the mineral acids 
and in hot solutions of fixed alkalies. When the precipitate from 
solutions of alum has been dried only at the temperature of the at- 
mosphere, it is found combined with nearly an equal weight d water, 
and then appears as a white powder or a gelatinous substance. There 
is a native hydrat of alumina found in different parts of the world, 
crystallized and traiisparent, and which has been called wavellite : 
from Mr. Gregor's experiments, and my own, it appears that this 
substance contains about 28 per cent, of water. 

No direct researches have been made on the quantity of oxygene : 
in alumina ; but from some experiments thdt I made ori the quantity 
of ammonia required to decompose saturated solutions of alumina in 
acids, it would appear that the number representing alumina is about 
48, and supposing it to consist of one proportion of aluminum, and 
one of oxygene, S3 will be the number representing aluminum. 

3. No substance is knovn that can be regarded as a compound of 
chlorine and aluminum. Alumina is soluble in solution of muriatic 
iicld ; but by Iieuting the salt obtained, muriatic acid gas rises, and 
silumiiici remains behind " 



1- 




k 



[ 203 J 

4. The compounds of alumina are found abundantly in the mineral 
kingdom, and many of them are of great importance in the comn on 
arts. Alumina forms a pan of the greater number of rocks, and is 
found in larger or smaller quantities, in almost all soils. In its crys- 
tallized form coloured by small quantities of iron, it constitutes a 
beautiful class of gems, distinguished by the name telesia, including 
the ruby, the sapphire, the oriental topaz, and other hard and bril- 
liant stones. 

Alumina combined with silica and other substances, forms the Ta- 
rieties of porcelain and china-ware. Its acid combinations are used 
to a great extent in dyeing and calico printing for fixing colours on 
stuffa. 

8. Glucinum, 

1, There is an earth which was discovered by Vauquelin in 1798, 
called glucine, or glucina. It may be obtained from tiie bci^l or 
the emerald, by the following process : the stone, in fine powder, 
must be ignited for half an hour in a crucible of silver or platina, 
with three times its weight of hydrat of potassa or soda. The mass 
jiiust be dissolved in solution of muriatic acid, and the compound 
obtained exposed to heat till it is dry. Water is then added to it, 
and the aqueous solution obtained acted on by solution of carbonate 
of potassa ; a white powder is obtained, which must be dissolved in 
diluted oil of vitriol not added in excess ; a little of the salt called 
vitriolated tartar, or sulphate of potassa, must be mixed with the so- 
lution) and the whole evaporated till it begins to crystallize ; crystals 
of alum will form. When no more can be obtained, the remaining 
Uquor must be mixed with solution of carbonate of ammonia added 
in great excess ; the mixed liquor must be passed through bibulous 
paper, evaporated to dryness, and the solid matter remaining heated 
to redness ; it is then glucina. 

3. There is great reason to believe that glucina is a compound of 
a peculiar metallic substance, which may be called glucinum^ and 
oxygene. The evidence that such is its composition, I have obtain- 
ed, by heating it with potassium in the same manner as alumina ; the 
potassium was for the most part converted into potassa, and dark co- 




[ 204 ] 

loiircd particles Iiavmg a metallic appearance were found lUffused 
through the mass, which regained tlie earthy character by hatx^ 
heated hi the air, and by the action of water, and in this last case hy- 
drogenc was slowly disengaged. 

3. Glucina in its pure form appears as a white powder without taste 
or smell ; it requires an intense degree of heat for its fusion ; h is 
not sc^uble in water in any perceptible degree ; it does not alter the 
colour of vegetable blues or yellows. When it is thrown down fixim 
an acid solution, by an alkali, it exists in combination with water, is 
a hydrat. It forms sweet-tasted salts soluble in water, with the 
acids, and hence it gained its name, from yAvxw, sweet. From ex- 
pcriments on the quantity of ammonia necessary to decompose tbe 
muriate of glucina, I am inclined to adopt 54 as the number repre* 
senting the earth, and supposing it a protoxide, 39 as the number 
representing the metal. 

4. No compounds have been as yet exammed in which glucinum 
can be supposed to exist, unconibined with oxygene. Glucina his 
not as yet been applied to any of the purposes of the arts, and its 
combinations in nature ai'e very rare. 

9. Zirconum, 

i . There is a peculiar earth, which was discovered by M. Klap- 
voth, in 1793, and which may be procured from a stone found in 
Ceylon, and called the jargon, or zircon, and likewise from the hya* 
cinth, by the following process. The powder of those stones must 
be Ignited for a long while with hydrat of potassa ; the substance 
which is not dissolved by tlie hydrate of potassa, is principally zir- 
con. The soluble matters must be separated by water, and the in- 
soluble matter boiled in muriatic acid, and the solution so obtained, 
evaporated to dryness, and heated to the temperature of 212°. Aft 
aqueous solution of zircona in muriatic acid, is obtained by the ac- 
tion of water on tlie solid mass; and pure zircona is procured by 
decomposing this solution by solution of ammonia, and heating tbe 
powder obtained to redness. 

2. Thcix; is the same evidence for believing that zircona is a com- 
pound of a metal and oxygene, as that afforded by the action of potas- 



C 205 ] 

sititm ott the other earths. The alkaline metal when brought into 
contact yrith zircona ig^ted to whiteness, is for the most part con- 
verted into potassa, and dark panicles, which, when examined by a 
magnifying gl^^ss, appear metallic in some parts, of a chocolate brown 
in bthersy are found diffused through the potassa and the undecom- 
pounded earth. 

3. Zircona appears as a harsh whitish powder without taste or 
smell ; it possesses no action on vegetable colours, and is insoluble 
in water ; its specific gravity is ratlier above 4. It is fusible at a 
lower temperature than any of the oUier earths ; the heat of a good 
forge is sufficient to soften it. In a mass it is very hard, and scratches 
rock crystal. Zircona is insoluble in water, but when precipitated 
fix>m its solution, and dried at a low temperature, is found in the 
state of a hydrat ; and has an appearance like that of resin or glue, 
its particles adhere together ; the hydrat contains more than •} of its 
weight of water. Zircona is soluble in the mineral acids and in so- 
lutions of alkaline carbonates. From experiments I have made on 
the comparative saturating powers of ammonia and zircona, I am 
disposed to give 85 as the number representing the earth, and 70 
as the number representing the metal ; supposing the earth to be a 
protoaude. 

4. No substance has as yet been formed or examined, in which 
xircooom can be supposed to exist free from oxygenc. It forms a 
crystalfiaed muriate when dissolved in muriatic acid ; but the muri- 
atic acid is expelled by heat, without any apparent union of chlorine 
and the metal. Its combinations therefore must be objects of future 
cnqniff. 

ZSrcona has not yet been found in sufficient quantities, to be ap- 
plied to any of the purposes of the arts. It combines with the other 
esrdif^ and forms compounds analogous to porcelain. 

10. Silicuni. 

1. Pure transparent quartz, or rock crystal, consists almost en- 
litely of a peculiar earth called silex or silica : this earth may be 
Kocured from that stone or from common flints by igniting them in 
finrder, with three or four times their weight of hydrat of potassa, 







[ 206 3 

or soda, in a silver crucible, making an aqueous solution of the sub- 
stance so obtained, and adding to it any acid in quantities barely suf- 
ficient to neutralize the alkali ; a g^clatinous substance separate^ 
which is silica combined >vith water ; and the pure earth may be 
obtained by washing this substance well, and then igniting it to white- 
ness. 

3. That silica consists of oxygene united to a peculiar inihuniBa- 
ble basis, which is probably metallic, is she>\ii by many experiments. 
When iron is negatively electrified, and fused by the Voltaic battery 
in contact with hydrat of silica, the metalline globule procured con- 
tains a matter which affords silex during its solution ; and when po- 
tassium is brought in contact with silica ignited to whiteness, a com- 
pound is formed consisting of silica and potassa, and black particle 
not unlike plumbago are found diffused through the compound. 
From some expenments I made, I am inclined to believe that thes^ 
particles are conductors of electricity ; they have little action up(9 
water, unless it contain an acid, when they slowly dissolve in it widi 
effer>'esccnce ; they bum when strongly heated, and become con- 
verted into a white substance having the characters of silica ; so 
that there can be little doubt, both fix)m analysis and synthesis, of 
the nature of silica; but no direct expenments have as yet bera 
made uix)n the proportion of oxygene it contains. 

3. Silica is a white powder, ver\' analogous in its physical charac- 
ters to the other earths; in its state of hydrate it is soluble in alka- 
line lixivia, and likewise in acids. It is separated from the common 
mineral acids by a veiy gentle heat, they rise from it in vapour, but 
it forms pci*manent compounds with boracic, phosphoric, and flucvic 
acids ; its compound witli phosphoric and boracic acids is a white 
powder, that with fluoric acid a permanent gas. From some expe- 
riments I liave made on the quantity of ammonia necessary.^ de* 
compose the saturated solution of silica in muriatic acid, and from 
the composition of its gaseous fluoric combination, as ascertained 
by my brother Mr. John Davy, I estimate the number representing 
silica as 61 ; and as it seems to combine with double proportions of 
acids, I am inclined to regard it as a deutoxide, composed of 31 ba- 
sis, and 30 oxygene. 

4. Xo compound of silicum and chlorine is known; and as this , 



[ 207 3 

substance has never been procured in masses, or even in an insulat- 
ed state, its action upon the other undecompounded substances has 
not been examined. 

5. Silica is one of the earths most generally diffused in nature. 
It forms perhaps the largest part of the solid surface of the globe. 
It is of great use in many of the arts ; it is the basis of glass and 
porcelain, and the art of manufacturing these substances depends 
upon the attraction of silica for other metallic oxides. 

11. Ittrium. 

1. There is a mineral substance called Gadolinitc, found at Itterby 
in Roslagen in Sweden, in which a peculiar earth was discovered in 
1794, by Mr. Gadolin, and to which the name of ittria has been 
given. To procure this eailh, the pulverized fossile must be di- 
gested for a considerable time in solution of muriatic acid. The so- 
lution obtained must be eva]X)rated to diyness, redissolved in distilled 
water, and precipitated by caustic ammonia; the precipitate obtained 
must be digested with solution of hydrat of potassa ; the remaining 
'substance must be redissolved in solution of muriatic acid not used 
in excess, succinate of soda must be poured into this solution till all 
precipitation is complete ; the filtered liquor must be decomposed 
by carbonate of soda, a white powder will fall down, which, when 
ignited strongly, is pure ittria, 

3. When ittria is treated with potassium in the same manner as 
the other earths, sinular results are obtained ; the potassium becomes 
potassa, and the earth gains appearances of metallization, so that it 
is -scarcely to be doubted that ittria consists of inflammable matter, 
metallic in its nature, combined with oxygene. 

3. Ittria appears as a white powder, without taste, smell, or power 
of action on vegetable colours; it requires an intense decree of heat 
for its fusion ; it is not soluble in water. No experiments have been 
made to ascertain whether it forms a hydrat with water, but this is 
most probably the case ; its specific gravity is greater than tliat of 
any of the other earths, being more than 4.5. It combines with the 
acids, and forms sweet-tasted salts with those in which it is soluble. 
With acetic and sulphuric acids it forms crystals of an amethyst co- 




[ 208 ] 

lour. It is not acted upon by solutions of caustic alkalies ; it is 
slightly soluble in solution of carbonate of ammonia. 

4. It is proliable that a compound of chlorine and ittiia may be 
obtained ; but as yet no experiments have been made on any com- 
fiounds of this substance, except such as contain oxygene ; the prot 
]X)ition of oxygene in ittiia cannot be determined from any experi- 
ments hitherto published. According to Klaproth, 55 parts of ittm 
combine with 1 8 parts of carbonic acid ; consequently^ if it be siip- 
{xysiAl that the carbonate of ittria consists of one proportion of acid, 
and one oi' earth, the number representing ittria will be 1 36 ; and co 
the hypothesis that ittria consists of one proportion of metal, and one 
ofoxy^ont;, which is probable from all analogy, the number repre- 
senting ittriuni will be 111. 

.'i. The compounds of ittria are very rare in nature, and as yet no 
application of this substance has been niade to any of the purposes 
of the uits. 

12. Manganeaum, 

I . The mineral called manganese has been referred tOy page 1S8; 
It (.(itiHisiH of u peculiar metal, manganeaum^ united to oxygene. To 
pnif'.urc: the pure metal, solution of muriatic acid must be disdDed 
fVcini nianguneHc hi fine powder, tlie mixture strongly heatedf andthe 
pniccHH iTpeutcd till the washings in pure water give only a white 
prcciptliUc witli u solution of the salt called prussiate of potassa and 
iniii ; iin aqurouH sohuion of i)otassa is then added to the mixture^ 
t.ii ;iii to rrniU'r it alkaline ; tlic whole is then poured on a filtre,ind 
till- mil III I lint I IP uhiiiiiu'd woU washed, dried, mixed with charcoal 
pinvili 1 it I III nil, ami intensely heated for half an hour in an infusible 
c-.iiilu-ii I rut il>lr luinl with eharcoal powder; a number of small 
lilt iitihi (^liitiiilrii will 1h' obtained, which are globules of mangane- 
{iiiiii 

-J .l/.j/ivi('.'..vf.m \Nas first piiH'urcd in its pure form by Kaim and 
< i.iliii, til i\w III IV.'O aiul 1775. It is of a grayish white colour, it 
luin iii'i iiitii li liiMiv ; its luu\lnoss is nearly that of iron; the specific 
\\\\\\\ \.^ aliniii 6.s,M», \\ Ls Yen- brittle. It requires a higher de' 
ivr lit tu .11 iliau iioit lor i:» t\i>ion. h immediately tarnishes in the 



t 209 ] 

aiT) and becomes gray, brown, and at last black; when strongly 
heated in contact witli oxygcne, it bums with great brilliancy, throw- 
ing off vivid sparks ; when heated in chlorine, it takes fire and bums. 
It dissolves with effervescence in the nuneml acids. 

3. There are two definite combinations of mangancsum and oxy- 
gene, one dark olive, and one brownish black. The iirsti or olix*c 
ojndfj may be obtained by dissolving common manganese in nitrous 
acidy adding a little sugar, and precipitathig by solution of potassa ; 
a white powder is obtained, which must be heated to redness out of 
the contact of air ; it is then the substance in question. The same 
body may be formed by precipitating the muiiatic or sulphuric so- 
lutions of manganese by potassa, and treating the precipitate by heat ; 
the white powder, when exposed to air, rapidly changes its colour 
to yellow, then puce colour, and lastly red brown : to be preserved, 
it should be washed in boiling' water, which contains little air, and 
the water driven off from it in a retort filled with hydrogcnc g^s. 

The dark otive oxide of manganeaum in its pure form, when exa- 
mined in large quantities, appears almost black ; but when spread 
upon white paper, its olive tint is apparent. It takes fire when gently 
heated) increases in weight, and gains a browner tint. It slowly ab- 
sorbs oxygene from the air, even at common temperatures. It is 
the only known oxide of manganesum which dissolves in the acids 
without effervescence. The white powder produced by tlie action 
of acids on solutions of this oxide is a compound of the oxide and 
water^ or the hydrated oxide qf nianganeaum ; and the different tints 
that it assumes by exposure to air, seem to depend ui>on the forma- 
tion of smaller or larger quantities of the dark brown oxide, which 
probably retains the water contained in the white hydrat, and in this 
state is deep puce coloured ; and when the water is expelled from 
it} it becomes dark brown, and then appear to be the same sub- 
stance as the native oxide of manganesum, which may be called the 
fitroxide of manganesum. The specific gravity of the peroxide is 
about 4 ; it is not capable of being combined with any of the acids ; 
it gives off oxygene gas by a strong heat, as has been already stated, 
and by intense ignition it is partly or wholly converted into the first 
or olive oxide of manganesum. From some experiments that I have 
made on the two oxides of manganese, I conclude that the olive oxide 



2 D 



\ 



C 210 ] 

consists of about 2 1 of oxygene to 79 of metal, and that the dark 
brown oxide contains nearly ten per cent, more of oxygene. Accord- 
ing to these estimations, supposing the olive oxide a deutoxide, or 
an oxide containing two proportions of oxygene, the number repre- 
senting manganesum will be 113; and the olive oxide will be repre- 
sented by 143 ; and the dark brown oxide by 158, that is, it must be 
a tritoxide, or an oxide containing three proponions of oxygene. The 
"White hydrated oxide of manganesum appears from my experiments 
to contain about 24 per cent, of water. Hence it may be regarded 
as consisting of one proportion of olive oxide of manganesum 143, 
and 34 of water, and the number representing it is 177. This hydrat 
is erroneously described in chemical books as the oxide of manga- 
nesum containing the smallest quantity of oxygene ; and, there are 
many other cases in which hydrats have been confounded with 
oxides. 

It has been supposed that there is a peculiar oxide of mianganese, 
which may be procured by alkalies from the sulphuric solution ; but 
when this solution is concentrated, the precipitate is the pale hydrat, 
having a very slight tint only of puce colour, apparently from the 
formation of a little of the other oxide in consequence of the absorp- 
tion of oxygene from the air dissolved in the alkaline solution used 
for its precipitation. It has been likewise conceived that there is a 
green oxide of manganesum ; the olive oxide becomes green by the 
action of potassa ; but in this case a combination takes place between 
the alkali and thie oxide. I have made many experiments on the 
native dark oxide by exposing it at different intervals for several 
hours to intense heat : in these cases it passed through different 
shades of broM'n and olive brown, and finally became dark olive. Co- 
lour is too indefinite a property to found a definite species upon ; a 
mere change of temperature, without any evident change in compo- 
sition, alters the colours of many bodies; and it is very probable that 
the different shades of colour of different precipitates from solutions 
of manganesum depend upon mixtures of the white hydrat with the 
puce-coloured hydrat formed at the time of precipitation by the ab' 
sorption of oxygene from the air in the fluid, and the white hydrat 
seems to be always the result of the action of alkali on solutions, in 




[ 211 ] 

cases when there can be no interference from the influence of free 
er loosely combined oxygene. 

4. A compound of chlonne and mangancsum may be obtained by 
combustion of the metal in chlorine, or by heating strongly the sub- 
stance obtained by the solution of mang^ese in muriatic acid. When 
made in tliis last way, it appears as a pale pink-coloured substance^ 
and semitransparent, and in brilliant scales. This compound has 
been described by Mr. J. Davy as consisting of chlorine and manga- 
nese, and from his experiments may be considered as consisting of 
one proportion of the metal 113, and two of chlorine 134. It is 
probable tliat another compound consisting of one proportion of the 
metal and two of chlorine may be formed. 

5. Hydrogene, azote, sulphur, and charcoal, have ik> distinct che- 
mical action on maiiganesum. 

6. Phosphorus has been combined with mangancsum by Pelle- 
tier ; the phosfihuret is a substance possessing metallic lustre and 
very combustible ; its constitution has not yet been ascertained. 

7. The action of boron, and the metals of the alkalies, and earths, 
on manganesom has not yet been tried. 

8. Manganesum in its oxidated form is of considerable use in cer- 
tain arts. Its application for the production of chlorine has been al- 
ready described. It is employed in glass-making, for depriving glass 
of colour : when in its state of full oxidation it gives a purple tint to 
glassj which is destroyed by thrusting a piece of wood into the melt- 
ed glass, the inflammable matter of which seizes upon a part of it3 
oxyg^e. 

It is in some cases used to give colours to enamels in the manu- 
&cture of porcelain. The changes of colour of glass containing ox- 
ide of manganesum, according to its different states of oxidation, are 
easily exemplified by adding a little dark oxide to powdered glass 
mixed with borax, and fusing them by the blow pipe : as long as 
the globule is preserved within the blue flame, where there is com- 
busdble matter, it remains colourless ; but when it is exposed to air 
at the extreme point of the flame it becomes purple. I am inclined to 
believe that the deutoxidc is the only oxide which enters into combi- 
nation with vitrifiable substances ; and that the peroxide when form- 
ed is mechanically diflused through the glass, and being produced 



[ 212 3 

only in very mioulc quantities is transparent and coloured. Thero 
is great reason to believe that the colouring matters of many gems 
are merely oxides finely divided in a state of mechanical diffuaon 
through their substance. 

13. Zinc or Zincum. 

1. Zinc is prbcured for the purposes of commerce from irarious 
ores known by the names of calamine and blende or black jack. 
To obtain the metal from calamine^ which is a combination of zinc 
with oxygene and carbonic acid, the ore is strongly ignited with 
charcoal or carbonaceous substances; the zinc, which is volatiki 
rises at a strong red heat, and becomes condensed in the cool part 
of the furnace or retort in which the process is carried on. Zinc is 
procured from blende by a similar operation, but the blende must 
be previously roasted, that is, exposed for a long while to a dull red 
heat in a state of minute division. The zinc of commerce is seldom 
quite pure ; to obtain it in this state white vitriol or sulphate of unc 
is dissolved in pure water and exposed to the action of a plate of 
common zinc ; this will separate any volatile metals that may hap- 
pen to exist in the solution, which is then to be precipitated by sub- 
carbonate of potassa : the white precipitate ignited with charcoal 
powder affords the metal. 

2. Zinc is of a bluish white colour. Its hardness is nearly equal 
to that of copper. Its specific gravity varies from 6.8 to rather more 
than 7. When hammered it is 7.2. Its fusing point is 680** Fah- 
renheit; at a red heat in close vessels it volatilizes ; and at this tem- 
perature in the atmosphere it bums with a brilliant bluish white 
flame. It has a certain degree of ductility, and when heated a little 
above 212° Fahrenheit, it is malleable, and when annealed it may be 
passed through rollere, and obtained m small thin sheets or leaves; 
it may be drawn into wire, the tenacity of which, according to Mus- 
chcnbroek, is such, that a wire of -^ of an inch in diameter will sup- 
port a weight of about 26lbs. Its capacity for heat, according tp 
Wilcke, is 0.102. 

The atmosphere has but little effect on ziiic at common tempera- 
; by exposure to the air for some time it acquires a grayish 




I 



C 213 -J 

colour on the surface) which ia owing to a partial oxidation. Zinc 
filings very slowly decompose water, hydrogene gas is evolved, and 
ozyg^ie combines with the metal. The effect is rapidly produced 
when steam is passed over zinc at elevated temperatures. Zinc in 
thin leaves introduced into chlorine takes fire, and bums with a white 
Ikght ; even when in thick wire it may be made to bum in this gasi 
by a gentle heat. 

3., There is one well-known combination of zinc with oxygene i 
it is obtained by the combustion of zinc in the atmosphere, or by the 
precipitation of solutions of zinc in acids by alkalies and subsequent 
ignition. When examined in a state of minute division, such as it 
appears when obtained by combustion, it is white, and similar to 
cotton in its appearance ; but when examined in mass it has a tint 
of pale yellow. It becomes fluid at a white heat, and is capable of 
being volatilized by an intense white heat. It is soluble in most of 
the acids, and in aqueous solutions of the fixed alkalies ; when pre- 
cipitated from its acid solutions by alkalies, it is in the state of com- 
bination with water, and a strong red heat is required for the expul- 
sion of the water with which it is combined. From my experiments, 
and those made by my brother Mr. John Davy, it appears that the 
white oxide of zinc contains about 82 parts of metal and 18 of oxy- 
gene. M. Proust gives 80 to 30, which is not a wide difference* 
On the estimation of 1 8 per cent, supposing that the oxide of zinp 
consists of one proportion of oxygene and one of metal ; the number 
representing zinc is 66 taking away the fractional part ; the oxide 
of zinc is represented by 8 1 ; and the hydrate, supposing it to con- 
tain one proportion of water, will be denoted by 17 added to 8 1 ; but 
as yet no experiments have been made to shew that this is the com- 
position of the hydrate. It has been supposed that there is a gray 
oxide of zinc produced by keeping zinc melted in the- open air; and 
a yellow oxide formed by fusing the white powder produced by pre- 
cipitation from acids, both ccmtaining less oxygene than the oxide 
just described; but there are no facts to warrant the idea that these 
bodies are distinct compounds of sdnc and oxygene. The gray 
powder formed upon the surface of melted zinc, I am inclined to 
consider as a mixture of the white oxide with small panicles of un- 






MVTat rinc, and the yellow oxide the same as the ojtide produced if 

combustion free from water. 

4. When zinc is burned in chlorine a solid substance is formed uf 
a whitish gray colour, and ae mi transparent. This is the only c 
pound known of zinc aud chlorine. It may likewise be msile bf.. 
healing together zinc filings and corrosive sublimate; it ia as sofiH! 
wax, fuses at a temperature a little above 312°, and rises in Qta! 
gaseous form at a heat much below the red heat. Its taste \i 
tensely acrid, and it corrodes the skin; it acts upon water and dis- 
solves iu it, producing much heat, and its solution decomposed by 
an alkali aflbrils the white hydrated oxide of zinc. The compound 
of zinc and chlorine has been called butter of zinc and muria 
zinc; following the nomenclature already proposed its name will be 
zineane ; from the experiments of my brother, Mr. John Davy,* 
consists of nearly equal parts by weight of zinc and chlorine ; coik 
seqncntly it contains onu prapoition of metal and one of gas 66 and 
67, and tlie number representing it will be 133. ' 

5. It is not easy to combine zinc and sulphur. When a Bolutuni 
of sulphuretted hydrogene and an alkali ia dropped into an acie 
solution of zinc, a whitish jxiwder falls down, which has been aop^' 
posed to be a aiil/iAurci of zinc. When zinc and sulphur are hested 
together in close vessels the sulphur rises in vapour without t 
ing to the zinc ; but it is staled by Mr. E. Davy, that in some ex- 
perimenls made in the laboratoiy of the Royal Institution, in which 
sulphur in vapour was passed over melted zinc, they united, and 
formed a white crystalline substance, analogous to the substauce 
found in nature, and called phosphorescent blende. The propor- 
tions of the elements in the blendes, or supposed sulphurets of zbc, 
have not yet been ascertained with accuracy; but if some experi- 
nienis oii record can be depended upon, they must contain two pFO- 
porUtms of niietal to one of sulphur. - -V 

«. Zinc combines with phosphorus, when the metal is fuied attd . 
the phosphoru^ brought in contact with it. TheMo*^*'"*^ <i/"zftw. 
was discovered by Pelletier; it is possessed of metal&c spIendouTt 
and is of a dull gray colour analogous to lead ; when hammered or 
filed it emits the odour of phosphorus. From esperiments ntade on * 
its composition in the laboratory of the Royal TnstitiUiiMi by i/tr. £ 



[ 215 ] 

Davy, it is probable that it consists of one proportion of phosphorus 
and one of metal. 

7. Zinc has not been combined with hydrogene, azote, or boron : 
zinc sometimes during its solution in acids leaves a residuum having 
the characters of carbonaceous matter : but no definite compound of 
zinc and carbon has as yet been described. 

8. Zinc readily enters into union with the metals of the fixed 
alkalies; great heat is produced during the process, and metallic 
compounds or alloys are obtained, which rapidly decompose water, 
and tarnish in the atmosphere. 

9. Zinc is applied to a number of important uses; it is particu- 
larly employed in the manufacture of brass and tombacs ; which con- 
sist of this metal combined with different proportions of copper* 
It is used by the Chinese in various alloys : some of its combina- 
tions are employed in medicine. 

14. Tin or Stannum, 

1. Tin is procured from the native combinations of this metal 
with oxygene, known by the names of tin stones, or oxides of tin, 
by ignition with charcoal or carbonaceous substances. The metal 
obtained from these ores is not pure. To obtain it in a state of 
purity, metallic tin should be boiled for some time in solution of 
nitric acid, the white powder formed should be well washed in pure 
water, and heated strongly in contact with about \ of its weight of 
charcoal powder in a covered crucible for about half an hour; a 
button of pure tin will be found at the bottom of the crucible. 

2. Tin has been known since the earliest periods of civilization ; 
it was used in the time of Moses : it is mentioned by Homer, and 
was brought from Cornwall by the Phoenicians and Greeks, some 
centuries before the Christian era ; it is called by Aristotle VLaurcert^w 
KfAriiMP, or Celtic tin. The colour of tin is white, and resembles 
that of ulver. Its hardness is greater than that of lead, and less 
than that of zinc. Its specific gravity is 7.291, and it is somewhat 
increased by hammering ; it is very malleable, and may be extend- 
ed into extremely thin leaves. Tin foil is about the -j^^ part of an 
inch thick; it has comparatively little ductility or tenadtr. It is 



[ 216 ] 

flexible, and when bent produces a crackling noise. It kas a slight 
taste, and when rubbed emits a peculiar smell. It fuses at 443" 
Fahrenheit, but requires an intense degree of heat £br its evapora- 
tion. Its capacity for heat, according to Dalton, is .07. It acquires 
a slight tarnish by exposure to the atmosphere, but undergoes no 
further change. It is not affected by water at common temperip 
tures, but when steam is passed over red hot tin it is decompoied, 
oxide of tin is formed, and hydrogene gas is evolved. When heated 
strongly in air, it takes iirc and bums with a pale white light; wiico 
burnt upon charcoal by a stream of oxygene gas, the colour of the 
flame is white, edged with violet. Tin foil bums when very gently 
heated in chlorine. 

3. There are two deiinite combinations of tin and oxygene: the 
first, which may be called the /irotoxidcy is gray ; the secandj which 
may be called the fieroxide^ is white ; the first is formed by headng 
tin in the air, or by dissolving tin in muriatic acid, and predpitatiiig 
the solution whilst recent, and before it has been exposed to w hf 
solution of hydrat of potassa, not added in excess. This substance^ 
after being heated to whiteness, is the protoxide of tin; and it b 
converted into the peroxide by being boiled with diluted nitric acid} 
dried by evaporation, and heated to redness. From experiments 
which I have made, it appears that the protoxide of tin contuns 
about 13.5 per cent, of oxygene, and from experiments made by 
Mr. John Davy, the peroxide is composed of about 24 of oxygene 
and 76 of metal. These oxides are difficultly fusible bodies, insolu- 
ble in water, soluble in diluted oil of vitriol, and in fixed alkaline 
solutions. Computing from their composition, and supposing ooe 
to consist of one proportion of tin and one of oxygene, and the 
other of one of tin and two of oxygene, the number representing tin 
will be 1 10, and the number standing for the protoxide will be 125, 
and that standintj for tlic deutoxide, or white oxide, 140. Both 
these oxides appear capable of combining with water to form 
hydrats; and wlicn precipiiatcd from their acid solutions, they 
always contain water, but cxperim'^nts are wanting to determine the 
quantity : both are insoluble in wa^i.r. 

4. As there are two combinations of tin with oxygene, so there 
are two which it forms with chlorine. When tin is bumt in chlorine 



[ 217 3 

a very volatile clear liquor is formed, a nonconductor of electricitfy 
and which, when mixed with a little water, becomes a solid crystal- 
line substance, a true muriate of tin containing^ the peroxide of tin. 
This liquor, which has been called Libavius's liquor, from its disco- 
verer LJbavius, may be likewise procured by heating together dn 
filings and cunvsive sublimate, or an amalgam of tin and corrosive 
sublimate. It consists, accuiding to the analysis of Mr. J. Davy, of 
two proportions of chlorine 134, and one uf tbi i lo ; and according to 
the proposed principles of nomenclature, its name vrUl be stannanea. 
The other compound of tin and chlorine is a gray semitraii»pai-cnt 
crystalline solid; it may be procured by heating together an amalgam 
of tin and calomel : it dissolves in water, and forms a solution which 
rapidly absorbs oxygene from the air, depositing oxide of tin. This 
compound of chlorine and stannane, it appears from the experiments 
of Mr. J. Davy, who first described it, consists of one proportion of 
tin 110, and one of chlorine 67; it may be called atannane, 

5. There are two aulfihureta qf tin: one may he made by fusing tin 
and sulphur together ; it is of a bluish colour and lamellated struc- 
ture ; and from the experiments of ray brother, consists of one pro- 
portion of tin and one of sulphur, 1 10 and 30. The other sulphurct 
of Xkkf or the supersulphurct, is made by heating together the per- 
oxide of dn and sulphur ; it is of a beauuful gold colour, and ap- 
pears in fine flakes; it was formerly called aurum musivum. It has 
been supposed by Pelleticr and Proust to contain tin in an oxidated 
state ; but Mr. John Davy has shewn that this is not the case, and 
•that it consists merely of one proportion of metallic tin combined 
with two proportions of sulphur, 1 10 and 60 ; so that the number re- 
presenting it is 170. 

6. Tin combines with phosphorus when the two substances are 
heated together. As yet only one compound is known, which ap- 
pears from my experiments to consist of 17 per cent, of phosphorus, 
and therefore may be regarded as composed of one proportion of tin 
and one of phosphorus, 110 and 20. The fihoafihoret of tin has '^ 
metallic appearance, is so soft that it may be cut with a knife; the 
phosphorus bums when it is gently heated in the air. 

7. Tin has not been combined ^vith hydrogenc, azote, carbon, or 
lioron: it readily unites to the metals of the fixed alkalies, and forms 



C 218 3 

alloys which speedily tarnish in the air, and which effervesce in water. 
It unites with zinc hy fusion ; the alloy is harder than zinc and stron- 
ger than tin. 

8. Tin is a metal of great use, and of various application ; it is aa 
important ingredient in pewter, bell-metal, and bronze ; it is employ- 
ed to cover culinary vessels, as tin plate ; some of Us acid comjiounds 
are used in dyeing. Tin is almost plways found in nature in the oxi- 
dated state, and in the crystalline form ; and it appears from the ana* 
lysis of Klaproth that the native oxide or tin stone of Cornwall must 
contain one proportion of tin and two of oxygene. All the well-knowD 
combinations of this metal are such as they ought to be according to 
the theory of definite proportions, and its compounds with oxygene, 
sulphur, and chlorine, afford similar results, Which correspond with 
tlie numbers gained from its simplest combination. 

16. Iron or Ferrum, 

1. The iron of commerce is obtained from various ores of that 
metal, in which it exists combined with oxygene, by intense ignition 
with carbonaceous substances : the purest iron is made from an ore 
called haematites by ignition with charcoal ; and the metal is ham- 
mered whilst in a soft state, exposed to air, till it becomes ductile. 
Iron was known in the time of Moses, and used for the manufecture 
of swords, knives, and axes. It is referred to in the Iliad and the 
Odyssey of Homer. A ball of iron was one of the prizes offered by 
Achilles at the funeral rites of Patroclus; and the effect of the burn- 
ing brand thrust by Ulysses and his companions into the eye of Poly- 
phemus, is compared by the poet to that of the hot iron plunged into 
^vater by the smith. The soft iron employed in the useful arts is 
free from any alloy, and therefore may be used for the purposes of 
chemistry. 

2. The colour of iron is well known, and its other sensible pro- 
perties ; its specific gravity is about 7,1. Its malleability, though 
considerable, is inferior to that of gold, silver, and copper. Its duc- 

id tenacity are, however, greater ; it may be drawn into ex- 

l^-fine wire, and a wire of 0.078 of an inch in diameter is capa- 

ipporting 549.25 lbs. It requires the highest heat of a wind 




[ 219 3 

furnace for its perfect fusion : it is attracted by the magnet and is 
capable of acquiring magnetism, though in its unalloyed state.it re- 
tains it only for a very short time. When iron is exposed to the at- 
mosphere it slowly combines with oxygene and carbonic acid, and its 
surface becomes covered with a yellowish substance well known by 
the name of mat. It burns with great splendour in oxygene gas, as 
has been stated, page 130. At common temperatures it slowly de- 
composes water. Hydrogene gas is evolved, and oxygene combines 
with the metal. The eftect is rapidly produced when tlie vapour of 
water is passed over red hot iron. When gently heated in chlorine 
it takes fire and burns with a deep red light. 

3. The combinations of iron and oxygene have been referred to, 
pag^ 61. The black and the red-brown oxidea are the only oxides of 
this metal known ; these substances, which have been considered as 
green and white oxides, are in fact hydrated oxides. The black 
oxide of iron, which may be regarded as a dcutoxide, as containing 
two proportions of oxygene, is formed by the rapid combustion of 
iron in oxygene. The red-brown oxide, which must be considered 
as a tritoxlde, may be produced from the black by keeping its pow- 
der red hot for a considerable time in contact with the atmosphere, 
often changing the surface. Reasoning on the composition of these 
oxides, 103 must be the number representing iron; and the black 
oxide, or the deutoxide, consists of one proportion of iron 103, and 
two of oxygene 30 ; and the brown-red oxide, or tritoxide, of 103 me- 
tal, and 45 oxygene. Both these oxides are soluble in the common 
acids. The black produces pale green solutions ; the brown-red deep 
yellow solutions : the solutions of triple prussiate of potassa, precipitate 
the solutions of tlie black oxide white ; those of the red bright blue. 
When solutions of these oxides are acted upon by solutions of pure 
alkalies, a white precipitate, having a tint of green or olive, is thrown 
down from the solution containing the black oxide ; and an orange-co- 
loured precipitate from the solution containing the red-brown oxide ; 
and both these precipitates, I find, are the oxides combined with wa- 
ter, or hydrates. The pale hydrate, when exposed to air, rapidly 
changes in colour, first becomes pale olive, then dark olive, then olive 
brown, and last of all orange ; so that there is strong reason to con- 
clude that the colours of different precipitates depend upon their be- 



[ 220 ] 

ing composed of mixtures of the two hydrates ; and sohitions of tht 
black oxide camiot be exposed to air for a moment without being 
changed by the absorption of oxygene. I have made no expeiim^its 
to ascertain the composition of the two hydrates ; probably the white 
contains two proportions of water. It would seem from the experi- 
ments of Dr. Thomson that there is a black hydrate formed by passing 
steam over iron ; and which probably consists of one proportion of . 
iron, two of oxygene, and one of water. M. Daubuisson has de« 
scribed a native hyd rated oxide of iron. 

4. There are two compounds of iron and chlorine. The one at- 
taining the largest proportion of chlorine is formed by burning iron 
wire in the gas. It is a very beautiful substance of a bright yel- 
lowish brown colour. It has a high degree of splendour, and is veiy 
volatile, rising in the gaseous state at a temperature a little above 
that of boiling water, and crystallizing in small irridescent plates. 
It acts with violence upon water, and forms a solution of red muri- 
ate of iron. I have called it ferranea^ and I find by analysis that it .. 
consists of one proportion of iron 103, and three proportions of chlo- 
rine 201. 

The other compound of chlorine and iron has been formed and 
analyzed by my brother, Mr. John Davy; it contains proportions 
which agree nearly with one of iron 103, and two of chlorine 134. It 
is a dark gray opaque substance, fusible at a red heat, and not rising 
in vapour at the point of fusion of glass. It forms a solution of 
green muriate of iron by its action upon water ; it may be named 
fcrrane. 

5. No combinations of iron with hydrogene or azote are known; 
but this metal readily combines with sulphur. There are two well- 
known sulphurets of iron ; one is formed by heating iron filings and 
sulphur together out of the contact of air ; they combine with great 
energ)', pioducing the effect of ignition. The suljihuret qf iron 
fonned in this way is of metallic splendour, and a dull yellow 
colour. This compound is found in nature, and has been analyzed 
by Mr. Hatchett. It is magnetic, and has been called magnetic 
pyrites. The other sulphuret of iron, which may be called the au- 
ptr:niI/Lhiirct, has not yet been made artificially, but it is found 
^ibundantly in metallic veins : it is of a bright yellow colour, and of- 



L 221 3. 

icji crystallized in cubes. According to Hatchett and Proust, the 
sulphuret of iron consists of about 63 of iron to 37 sulphur, and tlie 
supersulphuret of about 46 to 54; so that the quantity of iron remain- 
ing the same, the last sulphuret contain^ nearly double as much sul- 
phur as the first ; and iron being represented by 103, the propor- 
tions are not very remote from two of sulphur 60 in the sulphuret, 
and four of sulphur 120 in tlie hypersulphuret. 

6. Iron is capable of combining with phosphorus ; but the pro- 
portions of the elements of phosphoret of iron have not been ascer- 
tained ; nor is it known whether more than one compound of this 
exists. The phosphoret may be made by passing phosphorus in vapour 
over ignited iron. It is very brittle, of a dark steel gray colour, and 
of the specific gravity of 6.7. This substance, which was first found 
in the peculiar iron called cold short iron, because it is brittle when 
cold, was once supposed by Bergman and Meyer to be a peculiar 
metal ; but Klaproth discovered its re^vl nature. It may be formed 
likewise by heating together phosphoric acid, iron, and charcoal 

7. Iron is capable of combining with carbon ; and 8teel<^ perhaps 
the most important substance employed in tlic useful arts, is one of 
the results of their combination. Steel is usually made by a process 
called cementation, which consists in keeping bars of iron in contact 
with powdered charcoal in a state of ignition for ten or twelve 
days, in earthen troughs, or crucibles, the mouths of which arc 
closed with clay. Cemented steel is made into the substance called 
cast steel by being fused in a close crucible with a mixture of pow- 
dered glass and charcoal. Steel is possessed of the power of re- 
ceiving very different degrees of hardness by different applications of 
heat or cold. When it is heated to redness and suffered to cool 
slowly, it is found very soft; but if plunged into cold mercury or 
water, it acquires extreme hardness ; and by heating hard steel to 
different degrees, it receives different degrees of tt^mpcr, from that 
which renders it proper for files, to that wliich fits it for watch 
springs. In the process of tempering, the steel changes colour even 
though plunged under oil. Between 430° and 450° Fahrenheit, ac- 
cording to Mr. Stoddart, it assumes a pale yellowish tinge ; at 460° 
the colour is a straw yellow, and the metal is of the temper neces- 
sary for penknives, razors, and fine-edged tools. 'J'he colour gra- 



■ -■■■ V ■-» 



•s. 



n 



[ 222 ] 

dually deepens as the temperature rises higheri and it passes throu|^ 
brown, red, and purple, to 580, when it becomes of an uniform deep 
blue. These changes of colour seem to depend upon some change 
in the an*angement of the exterior layer of particles of the metal; L 
they cannot depend on oxidation, as they take place under mercury, L. 
Steel is of greater specific gravity than iron ; when tlie metal is fc 
hammered it is about 7.8. When it is acted upon by an acid, suck g 
as diluted nitric acid, a black spot appears upon it from the sept- 
ration of the carbonaceous matter. Steel is attracted by the magDet) 
and is capable of receiving permanent magnetism. It is not easy t» 
determine tlic exact quantity of carbon in steel, but it consists of ' 
several proportions of iron to one of carbonaceous matter. Difie^ 
cnt specimens of steel arc said, on the authority of Bergman, Vait 
(juclin, and Mushet, to contain only from ^-^ to -^jf of carbon. 

Iron has been converted into steel by cementation with diarooDd 
by Morveau and Sir George Mackenzie. 

Plumbago, or black lead^ as has been mentioned page 177, is a com- 
pound oi' carbon, with -^^ its weight of iron. There is a substance 
formed in iron foundries called kiah^^ of a brilliant appearance, usu- 
ally in thin scales, analogous to plates of polished steel. It consists 
chiefly of carbonaceous matter united to iron, and a little mangane- 
sum. 

8. When iron and charcoal are strongly ignited with boracic add, 
the iron produces, during its solution, boracic acid, as M. Descotils 
has shewn. Hence it is probable, as M. M. Gay Lussac and Th^ 
nard have supposed, that iron is capable of combining with bonm. 

9. Iron is capable of combining with potassium and sodium; 
these alloys are more fusible and whiter than iron, and effervesce 
copiously in water. There is great reason to believe that alloys 
may be formed of iron and the metals of the earth. Cast irony which 
is produced by fusing iron ores with pitcoal, during its conversicD 
into iTir.ller;blc iron c^flbrds about one fourth of its weight of a glass, 
which consists of silcx, alumine, lime, oxide of iron, and oxide of 
niani^ancsum. In the process for reducing cast iron into malleable 
iron culled bloom'mg^ the iron, after being fused in a forge by a fire 
of charcoal, is hammered, whilst in a soft state, on an anvil by a 
larirc Ivanimcr worked by water j a vivid combustion, which seems 



[ 223 ] 

Co be connected with the formation of the glass and the oxides takes 
place on the surface of the mass ; that the earths are formed by the 
oxidation of metals combined in the cast iron seems probable from 
the circumstance ot the combustion; and the idea is confirmed by 
the distinct metallic character of cast iron : it is white, crystallized, 
and has all the appearances of a perfect alloy. Specimens of cast 
iron usually contain likewise sulphur and carbon. 

10. Manganesum forms very readily binary combinations witli 
iron ; the alloys have a white colour, and aixj very brittle. Iron like- 
wise combines with tin. By fusing the two metals together, Berg- 
man obtained two alloys : the first containing 2 1 parts of tin, and 
one part of iron ; the second two parts of iron and one of tin. The 
£rst was very malleable, harder than tin, and not so brilliant ; the 
'Second scarcely malleable, and very hard. The fonnation of tin 
^late depends upon the chemical attraction between the two metals. 

Tin plate is formed by dipping thin plates of iron into melted tin ; 
the iron must be very clean. It is usual to add -^jg of copper to the 
%in, to prevent it from forming too tliick a coat. 

1 1 . To describe the uses of iron would require volumes ; as it is 
"*he most generally diffused metal, so it is likewise the most impor- 
^tant in its applications to the purposes of society. By means of it 
the earth has been cultivated and subdued. Without iron, houses, 
«ides, and ships could not be built. It is subservient both to tho 

O>nimon and the refined arts ; it forms the machineiy by which the 
;most important mechanical powers are generated and applied. Its 

"uses have awakened human industry, and made it more efficacious, 

and have dfTered an infinite variety of resources to ingenuity and 

talent. 

17. Lead or Plianbum. 

1. The lead of commerce is chiefly procured from certain ores, in 
which it is combined with sulphur. The sulphur is expelled or 
burnt by a long-contuiued heat in a reverberatory furnace, and the 
metal is obtained by fusion. To procure pure lead a solution of the 
lead of commerce in nitric acid, largely diluted with water, may be 
precipitated by zinc ; or a solution of acctite of lead, i. e. sugar of 



[ 224 ] 

lead, may be used. The arborescent brilliant metallic substance 
produced from solution of sugar of lead by zinc is generally pure 
lead. 

2. Lead was known in a very early age of the world. It is often 
mentioned by Moses ; and is described by Homer as in comrooD 
use at the period of the Trojan war. 

Lead is of a bluish white colour, but soon tarnishes by exposure 
to the air. It is the softest of the common metals. Its specific 
gravity is 11.352, and is not increased by hammering. It is veiy 
malleable, but not very ductile. Its tenacity is such that a viit 
of 1^.7 of an i»ch in diameter, supports only 18.4 pounds. Its point 
of fusion is 612% but an intense degree of heat is required for its 
evaporation. It combines with oxygene slowly, at the tempera- 
ture of its fusion, and bums when strongly ignited in the atmos- 
phere ; when a current of oxygene gas is thrown upon it In this state, 
the flame it emits is of a brilliant whiteness, and it sends off a dense 
smoke. When heated in chlorine it unites to it, but does not in- 
flame. 

3. Lead combines with oxygene in difl*erent proportions; and 
three of its combinations \vith this substance appear to be well-de- 
fined and distinct bodies. Two of the oxides of lead may be fonned 
by heat with accession of air ; the one is massicot^ the other ia m* 
iiiuniy or red lead. When lead is heated in contact with the atmo* 
sphere, it soon becomes of a dirty yellow, or yellowish green co- 
lour, and at length of a pure yellow colour. This oxide is massico(, 

I 

and is the oxide existing in the different salts of lead ; when preci- 
pitated from these salts by caustic alkalies, it falls down in combina- 
tion witli water, and appears as a white hydrated oxide of lead; the 
water may be expelled from it by a strong red heat. From the ex- 
periments of Vauquelin and Klaproth, it may be concluded that this 
oxide of lead contains about 7 per cent, of oxygene. Litharge is 
this oxide of lead, according to Dr. Thomson, mixed with a little 
carbonate of lead: litharge is formed during the extraction of 
silver from lead by the calcination of the lead, and the carbonic acid 
is acquired from the carbonaceous matter burnt in the flame of the 
furnace. 




I 



[ 225 ] 

Massicot is fusible at a strong red heat, and appears, when fused, 
as a yellow glass, insoluble in water, without taste or tmcll, and of 
great specific gravity. 

The first oxide of lead, Ijy being heated moderately in contact with 
air, for a considerable time, combines with an additional quantity of 
oxygenc, and then becomes of a beautiful red colour, in which state 
it is called minium, or red lead. 100 parts of lead carefully and 
slowly converted into minium become between 110 and 111 parts; 
so that there is strong reason to believe that the quantity of lead be- 
ing the same, the oxygenc in minium is to that in massicot, as 3 to 2, 
Minium exposed to a strong red heat gives off from 3 to 4 per cent, 
of oxygene gas, and becomes massicot. 

When nitric acid is digested upon minium, a part is dissolved, but 
a puce-coloured powder remains, which contains more oxygene than 
minium, and the formation of which seems to be owing to the cir- 
cumstance that the oxide, which dissolves during its solution, be- 
comes massicot, and alTords oxygene to the undissolved portion, so 
as to conyert it into a new substance. The fiuce-coloured oxide qf 
lead<i long dried at 312", loses from 6 to 7 parts per cent, during its 
conversion into massicot by fusion ; so that it may be considered as 
containing twice as much oxygene as that oxide, the proportion of 
lead being considered as the same. On these views massicot will 
be a deutoxide of lead, minium a tritoxide, and the puce-coloured 
oxide a tetroxide ; and the number representing lead will be 398; 
and the oxides will be composed respectively of 398 of metal, and 
30| 45> and 60, of oxygene. 

•4. One combination only of lead with chlorine is known ; it may 
be obtained directly by heating lead in chlorine, or by decomposing 
the oxides of lead by chlorine, in which case oxygene is expelled, or 
by acting on oxides of lead by muriatic acid gas, when water is 
formed. Thq combination of chlorine and lead is a dull whitish 
semitransparent substance, fusible at a heat below redness, and vola- 
tile at an intense heat. This substance has a sweetish taste, and is 
soluble in 22 parts of cold water. It was called horn lead by the 
old chemists, and improperly muriate of lead by modem chemists. 
The name proposed for it is filumbane. According to my experi- 
ments made on the absorption of chlorine by lead, it contains 401 of 

2 F 




[ 226 ] 

lead to 131 of chlorine, which agrees very nearly indeed with one 
proportion of metal, and two of chlorine ; and this compoiuid de- 
composed by alkalies affords the oxide containing two proportions 
of oxygene. 

5. Sulphur is easily made to unite with lead by a gentle heat 
One combination only of these bodies is certainly known, an4 it is 
the same as the substance found in nature* referred to in the be« 
ginning of this section, and called galena. It is very brittle, Ml- 
liant, and of a deep bluish gray colour. It is less fusible than lead, 
and crystallizes in cubes. 100 parts of lead in becoming the sul- 
phuret unite to about 1 5 parts of sulphur ; which gives the suipAu* 
ret J as consisting of one proportion of metal and two proportions of 
sulphur. 

6. A compound of lead with phosphorus may be formed by fusing 
together equal parts of filings of lead and phosphoric acid. It is of 
a silver white colour with a shade of blue ; may be cut with a kmfe, 
but is brittle under the hammer. The same substance may be form- 
ed by bringing phosphorus in contact with melted lead. AccordiDg 
to Pelletier it consists of 88 parts lead and 12 of phosphorus, wide 
gives nearly 3 proportions of phosphorus 60, to one of lead 398. 

7. There are no known combinations of lead, with hydiogefie, 
azote, carbon, or boron. 

8. Lead unites by fusion with the metals of the fixed alkalies, and 
forms compounds which tarnish in the air, and are readily decomposed 
by the agency of water. 

9. Lead combines with wnc, tin, and iron. Its alloy yrith iron is 
made with great difficulty, and has not been accurately examined. 
The alloys of zinc and lead may be easily made by fusion. These 
alloys are harder than zinc, and ductile. In whatever proportions 
the metals are melted together, the mass, on cooling, is found to 
contain them in a state of chemical union or intimate mixture. Lead 
and tin combine in a similar manner ; this alloy is harder and more 
tenacious than tin. It is said by Muschcnbroeck that these quali- 
ties exist in the highest degree in the alloy, when it is composed of 
5 parts of tin, and one of lead; which quantities nearly correspond 
with single proportions of each of the two metals. This mixture is 
often employed to cover copper vessels ; and, as appears from the 



[ 227 ] 

experiments of M. Proust, is difficultly acted upon by vegetable 
acids, and when acted upon, the tin is dissolved, and not the lead ; 
so that such vessels may be safely employed for culinary purposes. 
10. Lead is very extensively used both in the common and refined 
arts. Its oxides, and some of its saline combinations, are extensively 
applied in painting ; white lead is the deutoxide combined with car- 
bonic add. Both massicot and minium are common pigments. The 
deutoxide combined with chromic acid forms the most beautiful and 
permanent deep yellow known. Lead is used as an ingredient in 
various solders ; it is applied for covering houses and churches. It 
will be unnecessary to dwell upon its still more fisimiliar applications. 
Its oxide forms an important part of flint glass, and is used in vari- 
ous enamels and pastes. 

18. Antimony or jintimonium, 

1 . The ancients were acquainted with certain ores of antimony ; tlie 
most common of them, the sulphuret of antimony, was employed by 
the ladies of the oriental countries to tinge the extremity of the eye- 
lid blapk for the purpose of giving greater brilliancy of effect to the 
pupil. Basil Valentine is the first chemist who has described the 
process of extracting antimony from the sulphuret, though it does 
not appear that he was the inventor of this process. He published 
his Currus Triumphalis Antimonii towards the end of the fifteenth 
century. 

To procure antimony, the common antimony sold by druggists, 
which appears as a series of crystals, like needles, possessing thO 
metallic brilliancy, and which are composed of the metal and sul- 
phur, are ignited with half their weight of iron filings, and a quarter 
cf their weight of nitre added when they are in fusion ; the antimo- 
ny will be found in the bottom of the vessel in which the experiment 
is made. To obtain it quite pure, it may be dissolved in aqua re^ ; 
water is added to the solution, a white powder will fall down ; this is 
to be ignited for about 20 minutes, with twice its weight of tartar, 
when the metal will be produced. 

2. Antimony is of a brilliant white colour with a shade of blue ; 
its hardness is equal to that of zinc. Its specific gravity is about 




[ 228 ] 

6.8. It is very brittle, and may be easily pulverized. It has litde 
tenacity. It fuses at about 810*^ Fahrenheit. On cooling it crystal- 
lizesy and its laminated structure is owing to the new arrangemcDt 
of its parts. It is but little affected by exposure to the air or water 
at common temperatures ; but when the vapour of water is passed 
over red hot antimony, it acts so powerfully upon the water, as to 
decompose it with explosions. 

3. Two combinations of antimony with oxygene are known ; one, 
tht /unble oxide^ is obtained by dissolving antimony in muriatic acid 
by heat, and adding water to the concentrated solution ; a white pow- 
der fulls down, which, when washed with a solution of subcarbonate 
of potassa, and afterwards with distilled water, is a combinatioD of 
the fusible oxide with water, and by fusion at a red heat it becomes 
tlie pure oxide. This substiincc is of a diny yellowish white colour. 
It crystallizes by slow cooling after fusion. By being strongly heated 
in contact with the atmosphere it combines with more oxygene, 
rises in the volatile form, and condenses in white crystals of a silvery 
lustre ; and this substance is the fier oxide or antimony saturated with 
oxygene. This oxide is much less fusible, yet more volatile than 
the other, and is more difiicultly combined with acids. The fuuble 
oxide, in its combuiation witli water, was for a long while called the 
powder of Algaroth, from its discoverer AlgarottL Antimony buns, 
when heated strongly in the air, with a faint white light, and pro- 
duces the second or the volatile oxide, which rises from it in the 
form of a dense white smoke. From experiments made on these 
two oxides, by Mr. John Davy and myself, it appears that the fusible 
oxide contains | as much oxygene as the volatile oxide) supposing 
the mctul to be the same in both ; and calculating from his experi- 
ments on the fusible oxide, the number representing antimony is 
170 ; the fusible oxide may be considered as consisting of 170 me- 
tal, and 30 of oxygene, and the peroxide of 170 metal, and 45 oxy- 
gene. 

4, Antimony burns spontaneously when powdei^ed and thrown 
into chlormc. In this way the only known compmmd of antimony 
and chlorine, antimonanc^ or butter of antimony, is formed. It is a 
soft scmitransparcnt substance, of a yellowish white colour, very fu- 
fciblc, volatile at a moderate degree of heat. It crystallizes in paral- 



[ 229 ] 

leiopipeds. It is a very caustic and corrosive substance ; It acts 
with great energy upon water : with a small quantity of water it 
heats violently, and forms a solution ; a large quantity precipitates 
the fusible oxide of antimony, and muriatic acid is found in the so- 
lution. Antimonane may be likewise formed by the distillation of 
a mixture of powdered corrosive subUmatc and antimony. From 
the experiments of Mr. John Davy, it appears to contain 44 per 
cent, of chlorine, and therefore may be regarded as consisting of one 
proportion of metal and two of chlorine. 

5. Sulphur and antimony are readily combined by fusing tliem to- 
gether, when they form a compound of metallic appearance, similar 
to the natural sulphuret, and which is much more fusible than anti- 
mony : according to Proust it contains about 25 per cent, of sulphur, 
and may therefore be considered as consisting of one proportion of 
metal, and two proportions of sulphur, 1 70 and 60. 

6. Antimony has not yet been combined with hydrogene, azote, 
carbon, or boron. 

7. Antimony combines with phosphorus by fusion. According to 
the experiments of M. Pelleticr, the fihosphurct is white, brittle, and 
has the metallic lustre ; its composition has not been determined. 

8. Potassium and sodium may be combined with antimony by fu- 
sion ; they form alloys very similar to those they form with lead and 
tin. in their obvious properties. Antimony may be combined with 
all the other metals which have been described. The alloy of tin 
loid antimony is employed in the arts, particularly for making music 
plates. Antimony very much impairs the magnetic properties of 
ifOn; The alloy of lead and antimony is used for printers* types ; and 
for this purpose it is formed of 1 6 parts of lead and one of antimony. 
The oxides of antimony are used for giving a yellow colour to glass. 
Various combioations of antimony are employed in medicine. 

19. Bismuth or Biamuthium, 

I. The bismuth of commerce is procured from ores which usually 
contain it in the metallic state, or combined with sulphur, by roast- 
ing, and ignition with charcoal. The metal maybe obtained in a 
state of purity by dissolving the ore in strong niuuc acid^ and addinj^^ 



1 




L 5230 ] 

water to the solution, a white precipitate will appear, it is to be wash- 
ed, dried, and heated to a dull red for about 30 minutes, with a little 
oil, and some black flux, a substance made b^ heating together nitre 
and tartar ; a globule oi metal will thus be procured. 

2. The ores of bismuth were first described by Agricc^ befoce 
1530 ; the properties of the pure metal were not known before tb& 
middle of the last century. The colour of bismuth is white with a 
slight tint of red. It is nearly of the same hardness as copper. Its 
specific gravity is 9.832, and it is increased by hammeriDg. It is 
brittle, it cannot be drawn into wire. Its tenacity is such, that a rod 
'■^ of an inch in diameter sustains a weight of about 39 lbs. It fuses 
at about 476** Fahrenheit, and, if slowly cooled, crystallizes in cubes: 
if it is exposed to a strong heat in close vessels, it sublimes uul- 
tered. Bismuth acquires a superficial tarnish by exposure to the 
air ; it is not affected by water. 

3. One combination only of bismuth and oxygene is ceitunly 
known. When bismuth is kept at a dull red heat in open vessels, 
its surface soon becomes tarnished ; and, by exposing sur£Eu:e% the 
whole may be converted into an oxide. When heated more intensely 
in the atmosphere, or in oxygene gas, it bums with a bhiish flame, 
and a yellow oxide is formed, which fuses at an elevated tempera- 
ture. The oxides formed by slow or rapid combustion are of the 
same kind. When in powder, they are yellow ; when fused, they 
form a yellowish green vitreous mass. The oxide of bismuth re- 
quires an intense degree of heat for its volatilization. When this 
oxide b precipitated from its soluti^xis in acids by water or alkalies, 
it appears as a white powder, which probably is a compound oi the 
oxide and water. Klaproth has shewn that 100 parts of hSj iTnu th , 
by treatment with nitric acid and water, produce about 123 parts of 
the white powder. This powder has been called magistery of bis- 
muth. Geoffroy found 100 parts of bismuth become 1 10 parts 1^ 
exposure to heat and air ; but, in his experiments, probably some of 
the metal escaped oxidation. Mr. J. Davy has found the yellow 
oxide to contain, in 100 parts, 90 parts of metal, and 10 of oxygene, 
and tliis estimation is very near thr.r of Bucholz ; and supposing the 
oxide to consist of one proportion c r.;etal, and one of oxygene, the 

umber representing bismuth will be '35. 



[ 231 3 

4. Bismuth, when thrown in fine powder into chlorine, takes fiir^, 
and bums with a pale blue light ; in this case, the only known com- 
pound, bismuth and chlorine, is formed. It has been called hutter 
qf bismuth. It may be called biamuthane. It is an easily fusible 
substance, volatile at a moderate heat ; its colour is greyish. It 
corrodes the skin, and is readily decomposed by water; the bismuth 
combines with the oxygene of the water ; the chlorine with its hy- 
drogene. From the experiments of Mr. J. Davy, it appears that 
faismutbane contains 33.6 per cent, ot chlorine, and therefore may be 
considered as consisting of one proportion of metal, and one of the 
gas, 135 and 67. 

5. There are no Known combinations of bismuth with hydrogene, 
azote, carbon, or boron. 

6. Bismuth combines with sulphur when they are fused together; 
the 9ulfihuret is of a bluish grey colour, and has metallic lustre. 
According to Mr. J. Davy's experiments, it contains about 18 per 
cent, of sulphur* By this estimation, the sulphuret of bismuth must 
contain about one proportion of metal to one of sulphur. 

7. Bismuth appears to have little affimty^|p' phosphorus ; the at- 
tempts hitherto made to form this compound have been unsuccess- 
ful. 

8. The action of the metals of the fixed alkalies on bismuth is si« 
xnilar to that which they exert on other easily fusible metals. 

9. Bismuth forms alloys with all the metals which have been 
described, except zinc ; these alloys have been little examined. It 
sometimes enters into the composition of pewter ; and it forms a 
principal part of Newton's fusible metal. This alloy is composed 
of 8 parts of bismuth, 5 of lead, and S of tin, and melt^ at a tempe- 
rature below that at which water boils. 

10. Bismuth is not of much use in the arts. The white hydrat 
is employed as a pigment, but is not very permanent, becoming yel- 
low by the action of light. It is probable that the Roman ladies 
used the oxide of bismuth for whitening the skin ; for Martial, in 
speaking of a lady who made too free a use of cosmetics, describes 
her as afrjdd of the sun. 



[ 232 J 

This metal is sometimes employed in alloys to make easily fusible 
solders. The white hydrat has been lately employed in medicine, 
as a remedy in spasmodic affections of the stomach. 

20. Tellurium, 

1. Tellurium was discovered by Klaproth, in 1798^ and was pro- 
cured by him from an ore found near Zalethna, in Transylvania, in 
which it exists, in alloy with gold, lead, and silver. The process 
for obtaining the metal is very simple : the ore is dissolved in aqia 
regia made of a mixture of 1 part strong nitric acid and two parts 
muriatic acid. When the solution is saturated, water is to be addied, 
a white powder falls down, which, when dried, and heated in a retort 
of glass, with -j^ of its weight of charcoal powder, will aflford pure 
tdlurium. 

2. Tellurium is of a colour nearly the same as that of antimony. 
It, easily fuses, and rises in vapour at a strong red heat. It bums, 
when heated in the air, with a vivid bluish green ilame, sencting off 
a dense white smoke. ^Its powder takes fire in chlorine. Its spe- 
cific gravity is 6. 11 5. 

3. One oxide of tellurium only is known, the substance formed by 
combustion of the metal ; it is white, with u tint of yellow, when ex- 
amined in the mass. It fuses by a strong heat, and requires a very 
high temperature for its volatilization. When precipitated from its 
acid suluiions, it is found in union uith water, as a white hydrat" 
According to Klaproth, 178 grains of oxide of tellurium afford 148 
grains of nietal : supposing the oxide to consist of one proportion of 
oxygeViC, and one of metal, the number representing tellurium will 
be 74. 

4. When tellurium is burnt in elilorine, an easily fusible sub- 
stance is formed, which rises in vapour at a strong heat, and ci7stal- 
lizes. Its colour is wliiio ; it is semitn;iisparent ; when decompo- 
sed by water, it afTords tlie \\ hite hydrated oxide. Yvom my own 
experinu^nts, it appears this compound, or tdluranc^ consists of 2 
in wci;»ht of metal to 1.83 of chlorine ; it mr.y therefore be regarded 
as composed of or.e prc^portion of metal 74, and of chlorine 67. 



C 233 3 

5. Tellurium and hydtogene are capable of being combined. To 
make this combination, hydrat of potassa and oxide of tellurium are 
ignited with charcoal, and the mixture acted upon, by diluted sul- 
phuric acid, in a retort connected with a mercurial pneumatic appa- 
ratus ; an elastic fluid will be generated, which consists of hydrogene 
holding tellurium in solution* It is possessed of very singular pro- 
perties. It is soluble in water, and forms a claret-coloured solution. 
It combines with the alkalies. It bums with a blueish flame, depo- 
siting oxide of tellurium. Its smell is very strong and peculiar, not 
unlike that of sulphuretted hydrogene. I discovered this elastic 
fluid in August, 1809. When tellurium is made the electrical ne- 
gative surface in water in the Voltaic circuit, a brown powder is 
formed, which appears to be a solid combination of hydrogene and 
tellurium, and which was first observed by M. Ritter, in 1808: a 
claret-coloured solution of the gas is likewise formed when the water 
is free from air. The composition of tellurettcd hydrogene gas, and 
of- the solid hydruret of tellurium has not been yet ascertained. 

6. Tellurium has not been combined with azote, carbon, or boron. 
Kg experiments ai% on record as to its action on phosphorus. 

7. It unites to nearly its own weight of sulphur by fusion; the 
rcjsult is a lead-coloured striated mass. It seems probable that the 
sulphuret contains two proportions of sulpliur. 

8. Very few experiments have been made upon the alloys of 
tellurium. It combines readily by fusion with potassium and 
sodium, producing heat and light ; and forms with them difiicultly 
fusible alloys, which, when thrown into water, produce purple solu- 
tions consisting of the alkalies united to telluretted hydrogene. 

Tellurium has as yet been found in quantities too small to render 
it applicable to any of the purposes of the common arts. 

2 1 . Cobalt or Cobaltum. 

1. Cobalt is procured from its ores, which are for the most part 
combinadons of this substance with other metals ; or of its oxide 
with arsenic or sulphuric acids. It is difficult to obtain the metal 
in a state of complete purity. The pure oxide may be procured by 
dissolving the ore known by the name of arsenical cobalt la nitric 

2 G 



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i'.'. r..:'^\vr, coat, by -2:;ed i;f:6.;:s. f.rn-.s il.t basis of a hydra: di 
'>-:;"• ViU': loio.jr. By Lfc-tisr t.t '.j.c-a: .g-rsr/y in rAr air, k 
y- .\j.\'y \'.',.::.tz .1^--- lost b i-= • -^r. ^:^:1 absorbs oxygcne. Thb 
^.>>. J-'.*-:;: :^\ i:.'. ;..o:A-!-.y of cccomposir..^ murbiic acid; iu 
|M|^of o\;.:.;.r.t ',o::. .:..es v.iLi i:\e hyJro.^ene, unci the chlorine 

^wcc J ',:;. ^ ; y.f- t:r..tT::i <.:.: I un-, h.cliiitd 10 conclude, that 
■per*'- ::: .'; lAi-.u. yy.O.T fro^a cobal: is to that iii the blue 
% 2 •'. ! If K!^.;>:c.:r/3 expc-rimciiis be made tlie ground- 



: 



[ 235 ] 

work of calculation, and the blue oxide be considered as a dcutoxtdc) 
then the number representing cobalt will be 166, and the blue 
oxide will consist of 166 of cobalt and SO of oxygene; and the black 
oxide of 166 and 45. Mr. Thcnard states that there is an olive 
oxide of cobalt, produced by exposing the blue powder, which must 
be regarded as a hydrat, to air at conmion temperatures. And Mr. 
Proust has stated that there is a red hydrated oxide of cobalt ; it is 
probable that this last is a compound of the black oxide and water ; 
knd the substance supposed by Mr. Thenard to be an olive oxide, a 
mixture of the two hydrates. 

4. Cobalt combines with chlorine : the compound may be obtain- 
ed by introducing chlorine into an exhausted retort containing the 
metal in fine powder and gently heating it; a combustion takes 
place, but the results of this combustion have not yet been accurate- 
ly examined. 

5. Cobalt is not known to enter into combination with hydrogene, 
azote, carbon, or boron. 

6. Cobalt combines with sulphur and phosphorus, but with con- 
diderable difficulty. The sulphut*et is formed by acting on oxide of 
cobalt in a state of ignition by sulphur, and, according to Proust, it 
consiBts of 71.5 parts cobalt and 28.5 of sulphur; which indicate 
nearly one proportion of metal 1 66, and two of sulphur 60. The 
pho§fthurei is made by dropping phosphorus upon ignited cobalt ; it 
has not been minutely examined, nor its composition ascertained. 

7. The action of the metals of the alkalies and earths on cobalt 
has not been examined. 

8. There are no accurate experiments on the combinations of pure 
cobalt with the common metals. Lead unites with it, as Gmelin has 
shewn, and forms an alloy less malleable in proportion as it contains 
more cobalt. 

9. Cobalt in its metallic state is not employed in the useful arts. 
in its state of combination with oxygene, it is used to give glass, 
porcelain, &c. a rich blue colour. One grain of the pure oxide will 
give a deep tint of blue to 240 grains of glass. The solution of the 
oxide of cobalt in muriatic acid, forms one of the most beautiful of 
the symphathetic inks. This solution when concentrated is pale 
rose-coloured in the cold, but becomes blue green when heated ; lot 



[ 236 ] 

ters or fieuT^es traced br it upon paper are ir.Tisiblc in the cold, bttt 
be^xne oiue gretn when held before the nre. 

1. The cc»pper of cor:3inerce is procurtc from the mtirc com- 
bui.-.'.ions of tris Hietai wii-- iulpr.ur. cxjnreije. and certain acids, br 
rooSUD? and fusion either aione or wiih ii:L.e iskz. cartxAaceoios sub- 
stances: ii is i.ot ho'wevtr quite p»:re. To obtiiij it in a sate cf 
purity. dissoWe copper in strong mun^tic acid, diiute the aohidai 
with waier, and put iiito it a polished plate of iron, the copper will 
be precipitated ir. its metallic s .ate : it shculd be washed in «S2iBe 
muri-tic acic, ar.d thet: wiui pure Ti-aier* 

i. Copper is of a red colon.-; it is a little harder than sOrer; is 
«peci£c $:;ravity is about S.S9. When r:ibbed it emits an laipleisut 
smell« and it has a disagreeable taste. It is Terr malieahle* has cod- 
^derable ductility, and in tenacity is superior to all the meab ex- 
cept iron; it fuses at a lew white heat- By exposure to the air cop- 
per bt conies tamisl.ci. ind ifter sottie tin^e is coated with a gt«n 
crust, which consists c : Tr.e nict-ai in \^}izrL with oxygene and caiixxdc 
a:id. Ccp>cr is r.o; snc^ted by brir..^ kept in water, nor does it de- 
con:T>c.sc- t:.:? f.-li at arv :ciL;x;riti-re. — It buiT.s with a red flame 
eicw- '«iin ;:r:cr.. wherj fused ir^d actci ut>or. br oxr^eaae* wheni: 
thiri ii:avca :: ir.~in-.LS spoLUiie-:u£.y ii; c-Lkrirje. 

"-. Two cc--.pc»-r*Ls are kLo-wT*. ciicisiidr:^ c: oxygenc andco|^)er. 
Or;c is fviiTftl r^ii.t. aii:: is tne -:-r_- r:/./.:r -^i. It occurs in oc- 
ta:i.rc"s cf * croiicrable i'lstre : its >:-*i£Lr is du:l orange red 
A ::ri_.*r t:. Mr. C.'itiievix it z\>L-.:zlz^i 11.5 per ceiit- of oxyfreoe; 
accrcl .r M:. J. Da^T" a'>:;ut 11 per ce"t. I: is soluble in soluiioQ 
c: -.•-:—:.; itid ; ^.L -nreri tIJi siliiticn is precipitated, a pale 
crir. -r -::.:.: ni r^.-riir f-Jls ic-aT-s, ^r.::h :s this oxide united to 
-^ -..z. T:.-: :t t: :z:-t :•: ::;.;•=: i> :.rr..ec ir: the con«bustioD of 
•::tt-:-. ;r :; : .-:.-:: tie r:j::zi:i.:e :>cr.i a riirous solution of 



« 



-r - .^'- .. .■■ .>. .... ..:^.-_. .... ... .. percent- ci oxygene; 

•^-^^■■t-' :'-:-.,-.-:r :-cr.i a::.lj :;. r»::i?5o it is in cor^ibination 
4^T *^-- i= -.t!. >.-.•: f.-f ,• ^,c is i r.L-.i fruDc. contains i: 



[ 237 ] 

per cent, of water. If the red oxide of copper be considered as a 
protoxide and the black a deutoxide, the number representing cop- 
per will be 1 20, and this number will be found to correspond accu- 
rately with that gained from the analysis of the otlier combinations 
of the metal. The number representing the protoxide is 135, and 
that representing the deutoxide 150, and that repi^senting the blue 
hydrat 167. 

4. As there are two combinations of copper and oxygene, so 
there are likewise two combinations of this metal with chlorine ; 
both are produced by the same time, by the combustion of the 
metal in chlorine ; one is a iixed, easily fusible substance, like rosin 

■ in its exterior characters, the other is a yellowish sublimate. The 
first of these, as appears from the analysis of Mr. John Davy, con- 
sists of 36 chlorine, and 64 copper ; and the second of 53 chlorine 
and 47 copper ; the first may be called cufirane^ the second cu- 
firanea, Cuprane may be formed likewise by heating strongly to- 
gether a mixture of one part of copper filings, and two parts of cor- 
rosive sublimate; and it was in this way first produced by Boyle, 
•who appears to have been its discoverer. Cuprane is converted in- 
to cupranea by being heated in chlorine. Cuprane may be regarded 
as consisting of one proportion of copper 120, and one of chlorine 
67 ; and cupranea of one of copper 1 20, and two of chlorine 1 34. 
Cuprane is not soluble in water, but slowly becomes green by the 
action of the atmosphere ; when introduced into the flame of a candle, 
it produces a most beautiful light possessing almost all the pris- 
matic colours. Cufiranea dissolves in water and gives it a green- 
ish colour ; it is decomposed by a strong heat, and converted into 
cuprane by the expulsion of oxygene. 

5. Copper readily combines with sulphur, producing ignition when 
they are fused together ; and they form together a substance more fusi- 
ble than copper, brittle, and of a deep gray colour. This substance 
is likewise found native, and, according to the analysis of Mr. Che- 
nevix, contains about 19 per cent, of sulphur. The artificial ««/- 
fihuretj in some synthetical experiments which I made upon it, ap- 
peared to contain from 21 to 19 per cent. It may therefore be re- 
garded as composed of one proportion of copper 1 20, and one of sul- 
phur 30. It is probable that a supcrsulphui-et of copper may exist : 



[ 238 ] 

some of the golden-coloured copper pyrites, which contain as much 
as 41 per cent of copper, afford from 35 to 45 of sulphur: but they 
likewise contain iron. No su/iereulfihuret has as yet been made ar- 
tificially. 

6. Copper combines with phosphorus, by fusion. The fihosfikU' 
ret is of a white colour and very brittle, its specific gravity is 7.1330. 
Tt was first formed by Margraaf. According to Pelletier it contains 
20 per cent, of phosphorus ; and allowing this estimation it must be 
composed of two proportions of metal, and three of phosphorus^ 340 
and 60. 

7. Copper has not yet been combined with hydrogene, azote, car^ 
bon, or boron. 

8. It unites to the fixed alkaline metals, and to all the common 
metals that have been described. Some of its alloys with the common 
metals are well known. Copper is rendered yellowish white by al- 
loy with a small quantity of manganesum. United to zinc, copper 
produces brass, Dutch gold, Rupert's metal, and pinchbeck : from 
a third to a twelftli of zinc is used ; the paler the alloy required, the 
larger the quantity of zinc. 

Copper with a fourth of its weight of lead, forms pot metal. Cop- 
per alloyed with from -^ to ^ of tin forms the different species of 
bronze and bell-metal. The best composition for the mirrors of re- 
flecting telescopes is a combination of 33 parts copper, 15 parts tin, 
1 part brass, 1 silver, and I of arsenic. Tutenag, according to Keir, 
is a white alloy of copper, zinc, and iron. 

9. The account of the alloys of copper proves its importance in 
the arts. It is used unalloyed likewise for various important purposes, 
such as sheathing of ships, forming vessels when united with other 
metals, for culinary purposes, &c. In early ages the alloys of cop- 
per formed the principal arms offensive and defensive. I have ex- 
amined an ancient Attican helmet which consisted of an alloy of 
copper and tin. The swords and spear-heads of the early inhabitants 
of Greece and Italy seem to have been composed of the same ma- 
terials. 

All the saline combinations of copper are poisonous. 




/ 



[ 239 ] 



23. J\'ickei or Mckolum, 

JsTickel was discovered by Cronstedt in 1751, and examined in its 
pure state by Bergman, in 1775. Nickel exists in an ore called 
kupfemickel combined chiefly with sulphur, or in nickel ochrei in 
which it is united to oxygene. The metal may be obtained from 
these ores by roasting and ignition with charcoal ; but in this case 
it is &r from being pure. Pure nickci^ or at least nickel free from 
any other metallic substance, may be procured by nearly tlie same 
process as cobalt. The precipitate from the ammoniacal solution by 
solution of potassa, contains the nickel, and this precipitate must 
be intensely heated with charcoal powder. 

3. Nickel is of a white colour, and possesses considerable lustre ; 
Us hardness is little inferior to that of iron: its Kpccific gravity is 
about 8.38, but when forged it increases to 8.83. It is ductile and 
malleable. It requires a stronger heat for its fusion than iron— like 
that metal it is attracted by the magnet. When in fusion it bums 
like iron under a stream of oxygene g^s. 

5. Nickel when intensely ignited, exposed to air, l)cconi(:s a dark 
brown powder, which is still attractable by the magnet. Its soltitiuu 
in nitric acid decomposed by potassa aflbrds a pale grass green hy» 
drated oxide, which contains more than a fourth of its wuight of wa- 
ter, and which when heated to dull redness becomes an oxide uf a 
pale ash gray colour, and which, according to Tupputi, is composed 
of 21.3 parts of oxygene, and 78.8 of metal ; this oxide l)y stixiiig i(|;- 
nition becomes darker coloured, but when pure cannot be reduced 
to the metallic state by heat alone. Another oxide of nickel has 
been described by M. Thenard containing more oxygene. It muy 
be procured by acting on the hydrat of nickel by the sallH calK^d hytH 
peroxymuriates ; it is of a black colour ; its composition has not been 
accurately ascertained. From the nature of the compounds of nickel 
and sulphur, to be discussed immediately, it seems probable tlut the 
gray oxide is a deutoxide ; and if this be allowed, the number reprc- 
senting nickel will be 111, and the gray oxide will Le represented by 
two proportions of oxygene 30, added to one proportion of metal. 



[ 240 ] 

4. Nickel, when strongly heated in chlorine, smokes, and produces 
an olive-coloured substance $ but the composition of this substance 
has not been ascertained, nor its properties examined. When mu- 
riate of nickel is decomposed by heat some white brilliant scales are 
formed, which, as appears from experiments made by Mr. E. Davy, 
consist of nickel and chlorine ; but their composition has not been 
exactly asceitained. 

5. Sulphur combines with nickel by fusion, and forms a bright 
gray sulphuret, possessing metallic lustre. From experiments made 
on this aiU/ihuret by Mr. E. Davy, it appears to contain about 34 per 
cent, of sulphur, which gives proportions corresponding nearly to one 
proportion of metal 111, and two of sulphur 60, and harmonizes with 
the supposition that the olive oxide is a deutoxide. The same en* 
quirer states tliat there is a supersulphuret, which may be formed 
by heating the gray oxide with sulphur, and which contains about 
56.5 of nickel to 43.5 of sulphur, and which agrees nearly with on« 
proportion of metal to three of sulphur. 

6. Phosfihuret of nickel may be formed by causing phosphorus in 
vapour to act on metallic nickel in ignition ; the phosphuret is almost 
black, and has metallic lustre. Its composition has not as yet been 
accurately determined. 

7. Some specimens of nickel afford carbon during their solution 
in acids ; but no definite compound of carbon and the metal has been 
obtained. Nickel has not yet been combined with hydrogene, azote^ 
or boron, nor have any accurate experiments been made on its action 
on the metals of tlic fixed alkalies. 

8. It forms alloys with some of the common metals ; but few of 
these compounds have been examined with attention: with tin it 
pi'oduccs a white brilliant compound. Its alloy Mith copper is less 
ductile than pure copper, and is slightly magnetic. Its combination 
with iron is the most interesting of these compounds; these metals 
seem to unite in all proportions ; the colour of ihe alloy approaches 
nearer to that of silver in proportion as the nickel prevails, and the 
iron retains its malleability. In all the meteoric stones that have 
been examined, it is remarkable that the iron is alloyed by from 1 .5 
to 17 per cent, of nickel. The masses of iron found in Siberia and 
South America contain nickel, and there is the strongest probability 



[ 241 } 

■ 

that they are likewise of meteoric origin. The alloy of iron and 
nickel is much less liable to i-ust than common iron, and it is likely 
may be advantageously applied in the useful arts. The oxide of 
nickel is employed to give colours to enamels and porcelain ; in dif- 
ferent mixtures it produces brown red, and grass green tints. 

U4. Uranium. 

1. Uranium was discovered by Klaproth, in 1789. It may be pro- 
cured from the ores called Pechblende, and Uranochre, by the fol- 
lowing process. Let the ores be boiled in moderately diluted nitric 
acid, and solution of sulphate of soda added, and the precipitate, if 
any, separated. The clear solution is to be acted on by solution of 
potassa, the precipitate digested in ammonia, and the residuum heat- 
ed with strong nitric acid, and evaporated to dryness. The clear so- 
lution obtained from the mass by pure water when precipitated by 
solution of potassa will afford a yellow powder, and this made into a 
ball with wax, and intensely ignited in a crucible of charcoal, aiford^ 
metallic uranium, 

2. Uranium is of an iron gray colour and has considerable lustre ; 
it is hard and brittle. Its specific gravity, according to Klaproth, is 
8.1; its fuung point is higher than that of mangancsum. It under- 
goes no change by exposure to sdr, but when heated sti'ongly, bums, 
combines with oxygene, and assumes a blackish colour. 

3. Two compounds of uranium and oxygene have been examined by 
Klaproth ; the precipitate thrown down from the solution of uranium in 
nitric acid, when heated to dull redness, is still yellow, and this treat- 
ed with oil, and incinerated slightly, so as to bum off the oil, becomes 
a black oxide. It appears probable from Bucholz's experiments, 
that the oxygene in the black oxide is to that in the yellow as 1 to 3, 
and that the yellow oxide contains about 80 of metal and 30 of oxy- 
gene. I found that 8 parts of potassa precipitated 8.2 parts of yel- 
low oxide of uranium from the saturated nitrous solution ; and from 
this experiment, if potassa and the yellow oxide of uranium be sup- 
posed analogous in compositi^m, 76.8 will be the number for the 
metal, and the black oxide must be a compound of throe proportions 
of metal with one of oxygene. The substance that has beei^ called 

2 n 



» C 242 ] 

the native oxide, and which is crystallized in quadrangular plates, is, 
I find, a hydrated oxide. Bucholz supposes that there are several 
different oxides of uranium ; but he founds his opinion upon the ffi- 
ferent colours of precipitates, which may be mixtures of hydrates of 
the two oxides. 

4. ''No experiments have as yet been made on the action of ura- 
nium on chlorine, hydrogene, azote, boron, the metals of the fixed 
alkalies, or the common metals. 

5. A sulphuret of uranium may be procured by igniting the oxide 
with sulphur. It is a black heavy powder : its composition has xuA 
been ascertained. 

6. Uranium has been hitherto found in quantities too small to ren- 
der it applicable to the purposes of the arts. Its oxides give bright 
colours to glass, which according to the proportions are brown, ap- 
ple green, or emerald green. 

25. Osmium. 

1. This metallic substance was discovered by Mr. Tcnnant in 1804. 
It may be obtained from crude platina, by dissolving all the soluble 
parts in aqua regia, and distilling the black powder that remains with 
nitre, at a heat under redness ; a sublimate rises, which is soluble in 
water. When mercury is shaken with the solution, an amalgam is 
formed, and by distilling off the mercury, pure osmium is obtained. 

2. This metal has been procured only in very minute quantities ; 
it is of a dark blue colour, has not been fused, nor does it undergo 
any change at the most intense heat unless in contact with air, when 
it is converted into a volatile oxide. 

3. The composition of the oxide of osmium has not been ascer- 
tained ; it is a solid semitransparent substance, having a sweet taste 
and a strong smell : it is soluble in water, combines with potassa, 
and makes with it an orange solution in water. It tinges the skin 
of a dark colour ; and produces a pUrple with solution of galls. 

4. No combinations of osmium with any of the undecompounded 
substances described in the foregoing sections except that with oxy- 
gcne have been examined. The metal is not soluble in anv of the 

jjos ; but when fused with the hydrat of potassa becomes oxidated 



C 243 ] 

and combines with the potassa. It is a metal very easily reduced, 
being precipitated from the acjucous solution of the oxide by ether 
or alcohol. 

26. Tungsten or Tung'stcnum. 

1 . Tungstcnum is obtained from a mineral known by the name of 
woffram; it contains tlie oxides of tungsten, iron, and manganese, 
Avith earthy matter. To procure the metal pure, boil finely pulve- 
rised wolfram in strong muriatic acid for some time ; separate the 
solution ; the residuum contains a yellow powder ; it is to be washed, 
dissolved in ammonia, eva]>oi'atcd to drj-ness, then mixed with a lit- 
tle fine charcoal powder, and exposed to a veiy intense heat for about 
20 minutes in a covered Hessian crucible. Small grains of pure 
tung^tenum will be found at the bottom of the crucible. 

Tungstcnum in its metallic form was first procured by Messrs. 
D'Elhuyars, in 178'^. 

2. Tungstcnum is of a grayish white colour, and has considerable 
lustre. It is hard and i-athcr brittle. Its specific gravity is about 
17.3. It requires the strongest heat of a forge for its fusion. It is 
scarcely affected by exposure to air at common temperatures. At 
a temperature below redness its surface exhibits iridescent colours 
like iron. 

3. Tungstcnum combines with oxygene. When the metal in 
fine powder is heated to redness, it soon acquii'es a yellow colour, 
and is gradually converted into a yellow ofeidcj which is not soluble 
in water. Its specific gravity is 612, wijtier being 100. It is very 
diflficultly fusible. According to Messrs. D'Elhuyars 100 grabs of 
metal by calcinaUon form 124 grains of yellow oxide. Supposing 
the oxide a deutoxide, this result would give the number represent- 
ing tungstcnum as 125, and the number representing the yellow ox- 
ide as 155. Taking Klaproth's analysis of the combination of tung- 
btic acid and lime* as the basis of calculation, and supposing double 
proTiortions of the oxide to one proportion of lime, the number re- 
presenting the yellow oxide will be 124. From this it is probable 

* 17 of limr, 77 of tungstk oxide. 



that in D'Elhuyars' experiments the metal was not entirely convert- 
ed into oside ; and thai the number is about 94; but new experi- 
ments are wanting to elucidate this point. When the yellow oxide 
of tuiigstenuni is digested with solution of tin in muriatic acid, it 
. becomes blue from losing oxygenc. It is probable that in this state 
' it is a protoxide, but no accurate researches have been made on 
. tliis blue substance. 

4. Tungstenuni) I have found) bums with a deep red light when 
heated in chlorine, and forms an oi'ange -coloured volatile substance, 
wliich affords the yellow oxide of tungstenum, and muriatic acid, 
■when decomposed by water. I have made no experiments, nor axe 
any, I believe, on record on the composition of tungste-nane. 

5. Sulphur and phosphorus are both capable of being comlntnd 
' with tungstenum by being made to act upon it in a state of igtudmi 

but the properties nf the su/flfiurel and /ikogfihuret buve notbeen-. 
examined accurately. 

6. This substance has not been (^nmhinPtl with hydrogene, aaote, 
carbon, boron, or the metals of the fixed alkalies. From the expc- 
I'iments of Messrs. D'Elhuyars, it appears to unite with most of the 
common metals ; but its alloys have been only rudely exaauned. 

7. Tungstenum and its oxides have as yet been applied to no uses: . 
it was stated by Guyton dc Morvcau that the yellow oxide formed a 
mordant useful in dyeing ; that the red juices of fruits were fixed 
by it, 90 sa to make pennaneiit and beautiful lakes. The dyers who' 
have tried the experimfiiits in this countty have not, bpwever, ffcvea 
a favourable report of ttrajMsults. 



,.\ 



'■7. Titanium. -^ '■■ . • 

I. Tibmium is obtained from a'nuneral long known by the nomfr. 
of red tkorl, or titanite. The mmeral in ppwder is to be fused with 
five or six times its weight of aubcsrbonate of potassa.; the masa.is. 
to-be fully exposed to the action of water, and the solid matter re- 
maining digested and boiled with muriatic acid. The white powder 
not diasolvCH^ when mixed mthoil, uid intensely heated in i^ cructtile 
of charcoal, affords titanhim. The oxide of titanium xnn discovered 
by Mr. Giegor, in 17B1, jbanore&aad in tfaey^eyof Meoaclia* 



[ 245 ] 

ill Cctfnwall ; but metallic titanium was not produced till 1796, by 
"Vauquelin and Hecht. 

3. Uttle is known concerning the physical and chemical proper- 
ties of titanium ; it has only been procured in minute quantities, and 
in an imperfectly reduced state. Its colour resembles that of cop- 
per. It has much lustre. It is brittle. It tsunishes by exposure 
to air ; and requires the most intense heat of a forge even for its 
imperfect fusicm. 

3. Titanium combines with oxygene when it is exposed to heat in 
the atmosphere, and acquires a blue colour. The red ojcide^ which 
contains a larger proportion of oxygene, is found in the mineral 
kingdom. There is a powder of a white colour procured by fusing 
the red oxide with potash. This has been supposed to be a peroxide, 
but is probably a hydrated oxide; no precise experiments have 
been made on the composition of these bodies. This white powder 
is insoluble in acid and alkaline solutions ; and becomes yellow by 
being heated. 

4. The combination of titanium with chlorine has not yet been 
made. 

5. Titanium is not known to combine with hydrogene^ azote, car- 
bon, or boron. 

6. Titanium has not yet been combined with sulphur. It enters 
into union with phosphorus. The phosphuret is brittle, and has me- 
tallic lustre. Its composition has not been determined. 

7. The agency of the metals of the alkalies on titanium has not 
been examined. It has not been combined with any of the common 
metals except iron ; and this alloy is not characterised by any re- 
markable properties. 

8. Titanium has not been employed in the arts except for one 
purpose ; its oxide has been used at Sevres in the manufactuira of 
porcelain, to impart a brown colour. 

28. Columbium, 

1. Columbium exists in an ore brought from North America, of a 
black colour ; and likewise in two substances found in Sweden, call- 
ed tantalite and ittrotantalite. The metal may be procured by ignit- 





ing tlie ores vltli hj^dratct! fixed alkali ; and saturuting tlic alkafi- 
with nkric acid, a white powder falls rfowii. Tliis powder was first' 
obtained by Mr. Hatchctt from the American specimen, in 1802; 
and soon after the same aubslaiice was pi-ocurcd by Ekcberg from 
the Swedish mineral, and considered by him as a new substance. 
Dr. Wollaston, in 1810, demonstrated the identity of the two bo- 

'i. The white powder combines with alkalies and metallic oxides, 
and reddens litmus paper. Hence Mr. Hatched named it columtie 
arid. Attempts were made to reduce it by ignition with charcoal, in 
tlie same manner as the oxide of titanium, liut without success ; it 
became black, but did not acquire the metallic lustre. By passing 
potassium in vapour through the wliitc powder, heated to redness, I 
found that the potassium became converted into polassa, and a dark- 
coloured brilliant powder, like plumbago, was produced. This ia 
pi-obably tlie metallic basis of tlie substance, or pure columbium. 

3. No espeiinients have been made upon the combinations tft 
this substance. The white powder is soluble in boiling sulphuric 
acid ; and it is precipitated fi-om its solution ef an olive colour ty 
triple prussiate of potash, and of a bright orange by solution of galls 






1. There b a mineral found at Ridderhytta ib Swcdea, Yei^ ^ 
tungsten, of a reddish colour, and which has beta called ceritt. 
From this substance, Kissinger and Berzelius, in 1804, extncted ii 
brown powder, having the characters of a metallic oxide, and vti<£ 
they named oo-irfe of cerium. To procure this powder, the oreis 
digested with solution of nitromuriaUc acid; aiid the solufiiai obtain- 
ed evaporated to dryness, and heated with a little muriolic acid; ^ 
solution so procured is to be precipitated by solution bf iuiiiiMi^ 
the precipitate redissolved in muriatic acid, and acted upon by sta- 
tion of hydrbsulphurct of potassa ; the clear liquor, preupitatt^ by 
solution of carbfMiate of potaasa in excess, affords a white powder, 
which, when heated to redness, affords the brovm Oxide qf cerfmn. ' 

3. Cerium bad not been ■obtained in the metallic form till I'lOc- 
ceed^d in reducitig some oxide sent me by M. BerzeGusj'^bf tiiciuis 



C 247 ] 

»f potassium ; potassa was fonned, and a deep gray metallic powder, 
vhich became brown by oxidation. 

3. When the brown oxide of cerium is digested in the mineral 
icids, it becomes dissolved; and is thrown down from those solu- 
ions by alkalies, as a white powder : it is supposed that this powder 
:ontains less oxygene than the brown oxide ; but it is probably a 
hydrat. As yet, no experiments have been made cither on the 
composition of the brown oxide, or the white powder. 

4. No researches have as yet been made on the coml/inutions of 
cerium with the other undc compounded bodies. The solutions of 
cerium are not precipitated by solutions of galls ; they give a white 
precipitate with the triple prussiate of potassa. 

30. Palladium. 

1. Palladium was discovered by Dr. Wollaston, in 1803. It 
exists in the ores of platinum, both those from Peru and the Drazils. 
It may be procured by dissolving crude platina in aqua regia, and 
precipitating the saturated solution by solution of prussiate of 
mercury. The precipitate, washed, dried, and exposed to a strong 
heat, is convertecl into palladium. 

2. The colour of palladium is white, resembling that of platinum. 
Its hardness is rather greater than that of Ijar iron. Its specific 
gravity yarics from 1 1.3 to 1 1.8. It is very malleable, but has little 
ductility. It fuses at a high temperature ; but the precise point has 
not been determined. It is not affected by air or water at common 
temperatures. When it is heated strongly, its surface acquires a 
blue colour. 

3. Palladium combines with oxygene and chlorine by heat; but 
neither its oaddes nor its combinations with chlorine have as yet been 
examined. Dissolved in nitric acid it forms a beautiful red solution, 
from which the alkalies throw down an orange -coloured powder, 
which probably is a hydrated oxide. 

4. Palladium readily combines with sulphur when they arc heated 
together in a glass tube. The aulfihuret is rather paler than the 
metal, and very brittle: in an experiment that I made, 6.7 grains of 
palladium gained 1.5 grains, by being converted into the sulphuret ; 



ArA v^'jyXir.% tr.o sulphurct to consist of one proportion of metali 
2U'*< or.^ of i'jipnur, the nunaber representing palladiuminiS be 134. 

-:. Pailadium seems to have no action on hydrogenef azote, or 
cdrV>ri. Its relations of attraction to boron* and the metals of the 
Bxed alkaiiev have not yet been examined. It forms alkys with 
rriO.)t of th^ common metals ; but the properties of these compounds 
have not Viten examined with attention. 

Fsslladium has not as yet been found in sufficient quanuties to be 
^ipplied to the purposes of the arts. 

31. Iridium, 

1. Iridium v/as discovered, in 1803, bv Mr. Tennant; before Mr. 
Tennant had published his experiments, it was likewise cUlscovered 
by M. Descotils. 

Iridium exists in minute quantity in the crude ore of pbtma. 
To obtain it, the black powder (remainiiig after the solution of the 
ore of platina in nitro-muriatic acid) is to be mixed with about five 
times its weight of pure soda, and heated to redness in a ^vcr 
crucible for about 30 minutes. The dry mass is to be dissolved in 
diluted muriatic acid, and the undissolved residuum is to be aIte^ 
u'xU'Ay treated with alkali and acid; by which means it will be all 
iak(*n up. The solution, coiitiiming an excess of muriatic acid, is to 
be evaporated to dryness, rcdissolvcd in pure water, and slowly eva- 
porated, so long as any octohedral crystals form. These crystals I 
are muriate of iridium, and are reduced to the metallic state by cx- 
])osiii;^ them for a short time to an elevated temperature in a plati- 
num (:ruci!)le. 

2. Little is known conceming the properties of this metal. 
Iridium is of a white colour. It is brittle; and requires for its 
fusion a most intense heat : it is probable that its specific gravity is 
higher than that of platinum. It is not acted upon by oxygene eveii 
when heated to whiteness. From its relations to muriatic acid, 
which dissolves it, it seems that it is capable of uniting to chlorine. 

o. Iridium has not been combined with hydrogene, azote, sulphur, 
phosphorus, carbon, or boron, or the metals of the alkalies. It unites 
to lead, and forms a malleable alloy with copper. Dr. Wollaston 



C 249 3 

id amongst the grains of crude platina small white {Hmiclcs 
fie gravity 19.35 ; wliich consist of iridium alloyed with os- 
ind no other metallic substance. The osmium may be oxi- 
f the water in hydrat of potassa, and united with the potaasa ; 
iridium combined with chlorine by treatment with muriatic 
d thus dissolved. 

33. Rhodium. 

sodium was obtained by Dr. Wollaston, in L804, from the 
ilatina, by the following process. The ore is dissolved in di- 
la regia ; a solution of sal«ammoniac is added ; the clear U« 
sparated from the precipitate, is acted on by a rod of zinc, 
unc, a black powder is thrown 4own, which is washed with 
luted nitric acid. This black powder is re-dissoWed in dilute 
gia ; to this solution some common salt is added ; the whole 
eyaporated to dryness, and washed by alcoliol, till it has dis« 
lU the soluble matter ; there remidns behind a deep red sub- 
winch, when dissolved in water, and acted on by a rod of 
Sbrds a metallic powder, which, intensely ignited with borax, 
metallic button of rhodium. 

he specific gravity of rhodium exceeds 11. Its colour ap- 
» to that of silver, with a tint of yellow. It is not acted upon 
c or sulphuric acids. It is not known whether it combines 
ygene ; but solution of potassa throws down a yellow-coloured 
from the red crystals, obtained by dissolving in water the 
left after the washing by alcohol, and evaporating, so as to 
crystallization. From the actirni of nitro-muriadc acid on 
a, it is probable that it combines with chlorine, 
hodium unites with sulphur, and is rendered easily fusible by 
likewise combuies with lead, copper, and bismuth ; and its 
re easily soluble in nitro-muriatic acid. 



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[ 253 3 

3. Silver enters into r.ombination with oxyc^cne ; it absorbs this 
gaseous principle when kept intensely ignited in an open vessel for 
some time, and is converted into an olive -coloured glass. It bums 
vrith a fine green flame, and is convened into an oxide when acted 
upon by a powerful Voltaic instrument. 

The olive oxide of silver is likewise obtained by dissolving the 
metal in nitrous acid, precipitating by aqueous solution of baryta, 
and heating the precipitate to dull redness. From my experiments 
I conclude that 100 of silver absorb about 7.3 parts of oxygene to 
become the brown oxide ; and supposing this oxide to be composed 
of one proportion of metal and one of oxygene, the number repre- 
senting silver will be 205. No other oxide of silver except the 
brown is certainly known. 

4. Silver combines with chlorine when the metal is heated in con- 
tact with the gas. The compound, which may be called argcntane^ 
has been long known by the name of hornsiiver. It is a whitish semi- 
transparent substance, cuts like horn, is fusible at a red heat, and is 
insoluble in water. It contains about 34.5 per cent, of clilorine, and 
may be conudered as consisting of one proportion of silver 205, and 
one of chlorine 67. 

5. Silver is not known to combine with hydix>gene, azote, carbon, 
or boron. 

6. Silver and sulphur combine. This combination is effected, ac- 
cording to M. Proust, when silver is exposed for a considerable time 
to the atmosphere ; it is readily formed by heating to redness thin 
plates of ^Iver and sulphur. It is of a black colour, is brittle, and 
has the metallic lustre. According to the experiments of Wenzel, 
100 parts of silver by fusion combine with 14.7 parts of sulphur. 
The sulphuret of silver may therefore be regarded as constituted 
by one proportion of silver 205, and one of sulphur 30, 

7. Silver combines with phosphorus. This compound may be 
made, according to M. Pelletier, by heating to redness a mixture of 
silver, phosphoric glass, and charcoal powder. It is a white brittle 
substance ; its composition has not been determined with precision. 

8. Silver has not yet been combined with hydrogene, azote? car- 
bon* or boron. 



C 254 ] 

0. The action of the metals of the alkalies and earths on silver 
has not been examined. Silver forms alloys with most of the odicr 
metals, but the greater number of them have not been examined 
with much attention, or been applied to the purposes of the arts. 

The alloy of silver and copper is employed in coins. It is harder 
than pure silver, and better adapted to receive a fine impresdon. 

10. Silver is employed for a great variety of purposes in the use- 
ful and ornamental arts. It is largely used for ^Ivering copper, 
brass, and sometimes iron. In the common form in which it is ap- 
plied, it is alloyed with -f^ of copper, which gives to it hardnea^ 
without impairing its colour or its lustre. 

35. Gold, or jiurum, 

1 . Gold is found native, alloyed with copper or silver. To obtaoQ 
it in a state of purity, gold is dissolved in nitro-muriatic acidj the 
silver will remain an insoluble muriate, and must be separated; 
to the clear solution a solution of green sulphate of iron must.be 
added ; the gold will be precipitated in the state of a fine powder, 
and aflcr being well washed in diluted muriatic acid, and then in difr 
rilled water, may be fused into a mass. 

2. Gold is of a fine light yellow colour ; its hardness is scarcelj 
superior to that of tin. Its specific gravity is about 19.277, and it is 
somewhat increased by hammering. In malleability and ductility it 
is superior to all the other metals. It has a considerable degree of 
tenacity ; a wire of 0.078 inch in diameter ^vill support a weight of 
ISOlbs. It fuses at about 1300° Fahrenheit. It is not altered by ex- 
posure to air or water. 

3. There arc no accurate experiments recorded on the comhina- 
tlons of gold with oxygene. A purple oxide is formed when gold 
leaf is burnt by electricity, or gold wires by the Voltaic battery, but 
its composition has not been ascertained. No dependance can be 
put on the statements of chemists relative to pure oxides of gold, 
said to be obtained by treating solution of gold, with potassa, lime* 
and other substances, for in these instances, as far as my experience 
has JTone, triple compounds always appear to be formed. 



C 255 3 

4. Gold combines with chlorine when the metal, in a minute state 
of division, is heated in chlorine, or when the nitro-muriatc of gold 
is partially decomposed by heat, treated with muriatic acid, and eva- 
porated to dryness. It is a brown substance, is very deliquescent, 
and readily decomposes the water in the atmosphere, forming a mu- 
riate of gold. It has not been examined with precision. 

5. There arc no known combinations of gold with hydrngcnc, 
azote, carbon, or boron. 

6. There has been no distinct combination made of gold and sul- 
phur. 

7. Gold combines with phosphorus : this comi>ound has been i\ - 
cently made in the laboratory of the Royal Institution by Mr. £. L)av\, 
by heating gold, in a minute state of division, with phosphorus in ai: 
exhausted tube. It is of a gray colour, and has the metallic lustre. 
It is readily decomposed by the heat of a spirit lamp ; and contains 
about 1 4 per cent, of phosphorus. 

8. The metals of the alkalies combine witli gold ; but the allo\ ^ 
haye not been minutely examhicd. 

9. Gold forms alloys with the other metals ; many of them arc 
brittle, as those of bismuth, antimony, and lead. Others are mallea- 
ble, as those of silver, copper, and platina. The alloy of gold and 
copper is employed in coin. 

The applications of gold to the useful and ornamental arts. Sec. arc 
too well known to need particular detail. The purple oxide of gold 
is employed for colouring glass and porcelain. 

36. Platinum. 

1. The ores oifilatinum are very rare; they have been found only 
in South America and in Spain. The ores from South America 
consist of small roundish flattened grains. The ore found in Spain 
is in a vein principally consisting of silver. The only places in South 
America in which grains of the ore of platina have been discovered 
are at Choco in Peru, Santa Fe near Carthagena, and a district in 
the Brazils. 

Platinum is procured from the South American ore by dissolving 
it in aqua regia, and dropping into it a solution of sal-ammoniac ; u 



r 




C 256 ] 

yellow powder falls down, which must be redissolved in nitn>-mu?ia> 
tic acid) and again be precipitated by sal-ammoniac ; and after this 
second process, when ignited to whiteness, it is pure platinum. The 
particles maybe made to unite into one mass by hammering them id 
a state of ignition. 

2. Platinum was first described as a peculiar metal by^ Dr. Lewis, 
in 1754. 

Pladnum is of a white colour, but much less brilliant than ail* 
ver; it is not quite so hard as malleable iron: its specific^gravi^ 
after being hammered is 21.3, that of water being 1. It is^etf 
ductile and malleable ; may be easily drawn into wires about the 
.^^ of an inch in diameter, and hammered into very thin plates: 
its tenacity is such, that a wire 0.078 of an inch in diameter is ctp^ 
ble of supporting a weight of 274.31 lbs. avoirdupois without break* 
ing. It is not fusible by the heat of a forg^ ; and requires dther 
the intense heat of the concentrated solar rays, of Voltaic electridqri 
or of a flame produced by the agency of oxygene gas. 

3. Platinum combines with oxygene only with great difficulty. 
When intensely ignited by Voltaic electricity it fuses, and throws off 
sparks, and a fume rises from it, which is probably the oxide of 
platinum. 

When solutions of platinum are precipitated by alkalies, or alka* 
line earths, tlie precipitate always appears to be a compound of pla- 
tinum, oxygene, and earth or alkali employed ; yet Mr. Chenevix 
has stated, that by dissolving the precipitate from the nitro-muriatic 
solution by lime water in nitric acid, and driving olF the acid by heat, 
a brown powder is formed, which is an oxide of platinum, and which 
contains 13 per cent, of oxygene. The same ingenious chemist 
states that there is another oxide of platinum of a green colour, 
made by heating the brown oxide, and which he belierea comains 7 
per cent, of oxygene. I have seen several experiments made bf 
Mr. E. Davy, in which no precipitate was produced by the actioa 
of lime water on the nitro-muriatic solution : the lime water was 
used in various proportions, but without success. 

When an alloy of potassium and platinum is heated, exposed to 
air, both metals bum, and a yellow powder is formed, which gives 






[ 257 ] 

off Qxygene gas by ignition : but this powder, after being long ivash- 
cd, reddens turmeric, so that it is not pure oxide of platinum. 

4. A bright brdwn powder may be obtained by evaporating to dry- 
ness the nitro-muriatic solution of platinum. This powder, when 
heated to whiteness, is resolved into platinum and chlonne^ and the 
chlorine gas may be collected in a proper apparatus. From some 
experiments made on this powder, at my request, by Mr. £. Davy» 
it appears to contain about 24 per cent, of chlorine ; but this esti- 
xnate can be considered only as an approximation, for there are many 
difficulties in gaining accurate results on a substance so easily de« 
composed. 

5. Sulphur combines with platinum when they arc heated to- 
other in exhausted tubes. The auljihuret is an infusible black 
powder, decomposable by a white heat. According to Mr. E. Davy^ 
who first nifide it in the laboratory of the Koyal TnAtitution, it con- 
tains about JK per cent, of sulphur. He supposes that there is 
another combination of sulphur and platina, which may be made by 
heating the precipitate from the nitro-muriatic solution by sal-ammo- 
niac and sulphur together, and which contains 28 per cent, of sul- 
phur. 

6. Phosphorus and platinum combine with great energy, when 
the phosphorus is made to act in vapour, in exhausted tubes, on pla- 
tina, heated to dull redness : the combination is so violent that the 
mass becomes vividly ignited. The fihoajihoret of platina is an in- 
fCisible bluish gray powder witli little lustre. According to Mr. £. 
Davy, it contsdns more than 17 per cent, of phosphorus. He be- 
lieves that there is a eufierfihoafihoret of platina containing 30 per 
cent, of phosphorus, made by heating the yellow powder procured 
by sal-ammoniac with phosphorus ; but new experiments are wanting 
on this result, as well as on the results of the action of sulphur on 
platinum. The quantities do not correspond with the theory of de- 
finite proportions ; and as neither the metal nor the compounds made 
can be fused under the circumstances of the experiment, it is not 
possible to say that the combination is perfect; and as all such com- 
binations are decomposable by a strong heat, part of the compound 
irst formed may be decomposed before other parts of the mass en- 
ter into union. 

2 K 



[ 258 ] 

7. From Ihe experiments of M. Descolils it is probable that pla- 
tinum is capable of combining nith boron; it has never been uniieil 
to hydrogenc, azote, or carbon. 

8. Plutinuni readily miitea to potassium and soijinm ; their corabi- 
nation takes place with ignition, and a briglit Uriitlc mass is obtained, 
from which the alkaline metals are reaiUIy separated by the action 

,' of air or water. I'latJnum combines with most of the other mctal»; 
but the pi'opcrties of its alloys have been very little studied. To the 
fusible inctals it communicates difficult fusibility. It ainalgajniites 

' with racrcuT)- when heuted with that metal in a finely divided stale. 
It combines with gold, and renders its colour pa.le ; even ^V "^ P'^' 
nnm can be detected in union in gold, from the colour. 

9. Platinum is a most valuable metal : as it is not oxidablci dot 
fusible under common circnmstances, and only difticuIUy comhini^ 
with siilphoi", and n«t acted upon by common acids, kis admir^lfr 
adapted for the uses of tlic philosophical chemist, ani^Biybe advan- 
tageously employed in all cases ivliere gold is applietl, unless the tiae 
is connected with the colour or malleability of the nielal. The ge- 
neral application of platinum as a manufactured metal to the purposes 
of the laboratory is one of the many benefits which chemistry, 
useful arts owe to Dr. Wollastim. 

37. Arsenic or Araenieum. 

1 . Arsenic may be easily procured by beating the sidrataoce kunm 
by the name of white ar&eidc in powder with charcoal, i» b Florence 
flask, or a glass tube ; before the mixture becomes red hot, k metid 
sublimes, and CDndenses in the upper part of the vessel, wlucb is 

3. Arsciuc la of a Uuish white colour,not unlike that of ated. Itt 
specific gmvityia 8.31. It is very bnttle: its pcnnt of fiision has ant 
been aacertained ; but it is the most voladle of all the meOda, ri^c 
in T^our at about 3j6° of Fahrenheit's scale. When a pait of it is 
suddenly ignited, it bums with a pale Uuish Ught, sending off denao 
white ftunes. It bums sponttmeousljr in chlorine. 

3. There are two known combinations of arsenic and oxTgw; 
both of which are possessed of several of the propertlca of aiddB. 



L 259 J 

The first is the substance formed by combustion, and this coniuin^i 
the smallest quantity of oxygcne ; the compound containing the larg- 
est quantity of oxygene may be formed by distilling nitrous acid, 
mixed with -^^ of its weij^ht of muriatic acid from the other com- 
pound. The compound fonncd by combustion has been called arac 
nioua addj and likewise white oxide of arsenic. When procured by 
precipitation from acid solutions, it exists as a hydrat: it is fusible 
by a strong heat suddenly applied, but sublimes slowly at 383*' Fah- 
renheit; after fusion it appears as a white vitreous substance, of 
specific gravity 5. It is soluble in 80 parts of water at 60**, and in 
15 parts at 212°. Its taste is acrid, leaving an impression of sweet- 
ness. When heated its smell is like that of garlic. The compound 
of arsenic with the largest proportion of oxygene is called antmic 
acid. It is much more fixed in the fire than arseiuous acid, is very 
soluble in water, and has an intense sour taste. From experiments 
on the quantity of oxygene absorbed by arsenic during its conversion 
into these two compounds, made by Proust and by myself, I con- 
clude that the arsenious acid consists of about 25 of oxygene and 75 
of metal; and the arsenic acid of 33 of oxygene and 07 of metal. 
Hence it appears that the quantity of metal behig the same, the oxy- 
gene in the arsenic acid is to that in the arsenious nearly as 3 to 2 ; 
and if the arsenious acid be supposed to contain two proportions of 
oxygenC} the number representing arsenic will be 90; and those 
representing arsenious and arsenic acids will be 120 and 135. 

4. The only comix)und of chlorine and arsenic known, is made 
by the combustion of the metal in chlorine, or by distilling a mixture 
of arsenic and corrosive sublimate together: it is a heavy limpid 
fluid, capable of being easily rendered gaseous, formhig a liquid 
muriate of ai-senic by the action of a small quantity of water, and af- 
fording a precipitate of arsenious nearly acid by the action of a large 
quantity. From my experiments it appears that the compound of 
chlorine and arsenic, which may be called araenicanc^ consists of 40 
metal to 60 of chlorine ; therefore it may be regarded as composed 
of two proportions of chlorine, and one of metal. 

5. Arsenic combines with hydrogene. The best known substance 
containing tlie two bodies is araeniuretted hydrogen e gas. This elas- 
tic fluid, which was discovered by Scheele, may be procured by dis- 



r 



[ 260 J 

solving an alloy of 14 parts of tin and 1 of arsenic in inumtic add. 
This substance has an extremely fetid smell; it burns when broBglit 
near an inflamed taper in the atmosphere ; its flame is blue; and if 
the vessel in which it is burnt have a narrow neck, it depoats an^ 
nic. It inflames spontaneously when acted upon by chloiine; itis 
soluble only to a very slight extent in water It is probable thattte 
gas called araemiirettcd hydrogcne is always a mixture of a trae 
gaseous compound of arsenic and hydrogcne, with commGD hydro- 
gene. Its specific gravity varies, as I have found, from 5 to 8, that 
of hydrogene being 1. When decomposed by attracting the arsenic 
from it, by the action of ignited metals, there is an expansion of »• 
lunic. M. M. Gay Lussac and Thenard found 100 parts of it decooh 
posed by tin become 140 parts. M. Stromeyer states that he ana- 
lysed a gas consisting of 106 parts arsenic, and 2.19 hydrogene. 
This would agree with the idea that the pure gas is composed of 2 
proportions of hydrogene, and one of metal ; but such a gas must be 
more than twice as heavy as any specimen that has been weighed; 
and this circumstance leads me to doubt of the correctness of M. 
Stromcyer's results. 

There is likewise a solid compound of hydrogene and arsenic: it 
may be procured by acting on water by an alloy of potassium and 
arsenic in great excess : it is a brown powder, which bums, when 
gently heated in the atmosphere, and which gives off arseniuretted 
hydrogene, when heated in close vessels. The same substance is 
procured when arsenic is made the negative surface in contact with 
water in Voltaic combinations. No exjjeriments have as yet been 
made on tlie proportions of its elements. 

6. Sulphur and arsenic readily unite by fusion, and form a red 
vitreous semitransparent mass. The same substance is found native 
in different parts of Europe, and is called realgar ; it is often crytal- 
lizcd in transparent prisms : its specific gravity is 3.225. If The- 
nard's account of its composition be considered as accurate, it must 
consist of two proportions of arsenic, and three of sulphur, 180 and 
(yO. If sulphuretted hydrogene gas be made to act upon a solution 
of arscnious acid in muriatic acid, a fine yellow powder falls to the 
l;ottom. This powder is usually called orpiment. It maybe formed 
:ikcv.isc by subliming arsenic and sulphur together in a heat not suf- 




C 261 ] 

ficlcnt U> produce a fusion of the mass. It is composed of thin 
plates, which have a considerable degree of flexibility. According 
'to Thenard it contains muro sulphur than realgar ; but Mr. Proust 
states that by fusion it becomes realgar. 

7. Arsenic readily combines with phosphorus, and they form to- 
gether a black powder ; the proportions of its elements have not yet 
been accurately ascertained. 

8. Arsenic has not been combined with azote, boron, or carbon. 

9. Arsenic combines with most metallic substances. It renders 
the metals of the fixed alkalies less fusible by uniting to them, but 
its alloys with the common metals are usually very fusible. It ren- 
ders gold and platina brittle, and gives whiteness to copper : none 
of the alloys containing it in any considencble quantity arc malleable. 

10. Arsenic is not much used in the arts. Realgar and orpiment 
are employed as pigments. The solutions containing arsenious, or 
arsenic acids, are extremely poisonous. The arsenious acid, in very 
small doses, has been employed in medicine, particularly for the 
cure of intermittent fevers. 

38. Alohjbdenum. 

1. There is an ore found in different parts of Europe, paiticularly 
in Sweden, not unlike plumbago, from which Schcelc, in 1 778, pro- 
cured a white powder ; and from this powder Hielm, in 1 782, ob- 
tained a metal, which he called molybdenum. 

Pure molybdenum may be obtained eitlier from the ore like plum- 
bago, or from another ore found in Carinthia called the molybdat of 
lead ; by digesting them in powder in nitric acid, and boiling the 
mass in sulphuric acid ; by lixiviation with water a liquor is obtained, 
which when acted on by solution of ammonia passed through a filtre 
and mixed with nitric acid, deposits a white powder, and this powder 
intensely ignited in a charcoal crucible mixed with linseed oil affords 
the metal. 

2. Molybdenum, according to the observations of Bucholz, is 
brittle ; its specific gravity is 8.6 11. Its colour is white. It bums 
when placed on ignited charcoal and acted on by a current of oxy- 
gene gas, and gives off a white smoke which collects in small nee- 
dle-formed crvstals. 



[ 262 ] 

3. There are two well-defined combinations of molybdenum and 
oxygenc. One is blue, the other is pale yellow ; they both possess 
acid properties, and therefore may be disting;uished by the names of 
molybdoiis and molybdic acids. The molybdic acid is easily obtained 
from the ores of the metal by treatment with acids and ammonii : 
the white powder described in the last page is this substance com- 
bined with water, and it may be procured pure by ignition. Its spe- 
cific gravity is 3.4 ; its taste is sour ; it is fusible in a strong hesti 
and volatilized by intense ignition : it is soluble in about 1000 times 
its weight of water. 

The blue acid, or the molybdoua acid^ is formed by triturating to- 
gether in boiling water, one part of molybdenum in powder, and tvo 
parts of molybdic acid. The solution is to be passed through a fil- 
trc, and evaporated in a temperature not exceeding 1 30** ; the blue 
acid remains in the state of a fine powder. This acid is more solu- 
ble in water than the molybdic acid, and acts more intensely on ve- 
getable blues, converting them to red. According to Bucholz the 
blue acid consists of 100 parts of metal to 34 of oxygene» and the 
yellow acid of 100 parts of metal to 50 of oxygene. On these data 
it seems probable that molybdous acid consists of 2 proportions of 
oxygene and one of metal ; and molybdic acid of 3 proportions of 
oxygene and 1 of metal ; and assuming the composition of the mo- 
lybdous acid as the foundation of calculation, the number represent- 
ing molybdenum will be 88.2. Mr. Bucholz supposes that there 
arc oxides of molybdenum, containing smaller quantities of oxygene 
than the two acids. It is probable that there is a brown oxide con- 
taining a single proportion of oxygene, obtained by exposing the 
metal to a red heat ; but what Bucholz considers as a violet bro^m 
oxide produced by heating the brown oxide, is probably only a mix- 
ture of the brown oxide and the blue acid. 

4. No direct experiments have, I believe, been made on the ac- 
tion of chlorine on molybdenum ; but when the molybdic acid is dis- 
solved in muriatic acid, and the residue heated to redness, chlorine 
rises, and the blue acid remains behind ; but a grayish sublimate is 
r«^^(||C formed, in which chlorine is indicated by the action of ni- 

Iver. 

rtybdenum rombines readily with sulphur by fusion, or by 



[ 263 ] 

iieating^ strongly together molybdic acid and sulphur. The sulphurel 
of molybdenum is a black shining powder, the same as the native 
xnlneral from which Scheclc first procured the acid. According to 
Bucholz it contains 60 of metal and 40 of sulphur per cent, and there- 
fore may be considered as consisting of one proportion of metal and 
two of sulphur. 

6. Phosphorus combines with molybdenum; but the properties 
and constitution of tlie fihoafihoret have not been investigated. 

7. Uydrogene, azote, carbon, and boron, have not been combined 
with molybdenum. 

8. It unites to several of the metals ; one of the most perfect of 
its alloys is with iron. With lead it forms an alloy somewhat mal- 
leable. Most of its other alloys break under the hammer ; from the 
difiicult fusibility of the metal it is not easy to make them uniform 
in their constitution. 

Molybdenum has not yet been applied to any of the purposes of 
the arts. 

39. Chromium. 

1 . There are two ores from which chromium may be procured ; 
one 18 the red lead ore of Siberia, the chromat of lead, the other is 
the chromat of iron, which has been found in France and in North 
America. 

Chromium was discovei*ed by Vauquelin, in 1797. To obtain 
chromium, chromat of lead in fine powder is to be digested with 
moderately strong muriatic acid, till its power of action is exhaust- 
ed. The fluid produced is to be passed through a filtre, and a little 
oxide of silver, such as is procured by precipitation from nitric acid 
by ptttassa, very gradually added to it till the whole solution becomes 
of a red tint. This liquor by slow evaporation deposits small ruby 
red crystals, which, when intensely ignited, mixed with a little 
charcoal powder, afford chromium, Chromat of lead may be pro- 
cured from chromat of iron, by decomposing it by hydrat of potassa, 
maldng a solution in nitric acid, and adding solution of nitrate of lead ; 
the chromat of lead falls do^vl\ as a beautiful orange powder. 



/ 



[ 264 ] 

2. Chromium is a white brittle metal, requiring an intense hett 
for its fusion ; it is very difficultly acted on by acids. It docs sot 
readily enter into combustion. Its specific gravity is 5.9. 

3. Very few experiments have been made on the combinations of 
chromium. The red crystals procured from chromate of lead bf 
muriatic acid appear to be a hydrated acid ; they are soluble m 
water, have a sour taste, and combine with alkalies. 

The red crystals strongly heated become a green powder, wUcb 
is considered as an oxide qf chromium. It is said that from 100 paitl 
of the red crystals 67 parts of metal may be procured. The addrf 
chromium, when combined with alkalies, precipitates most of the 
metallic solutions. In solutions of mercury it produces a verminkn 
red precipitate ; in those of ^Iver, a carmine red ; in those of tu, a ' 
green. The name chromium has been given to the metal from its 
remarkable colouring powers*. 

4. The artificial chromate of lead forms a beautiful and permiMOt 
pigment. I have found the orange colour most pure "when the ni* 
trate of lead used for the precipitation contained an excess of addi 
The oxide of chromium has been employed for giving an emeraU 
green colour to glass and enamel. Chromic acid is the colouiing 
matter of the spinelle ruby ; and oxide of chromium gives its beto- 
tiful colour to the emerald. The oxide of chromium has been latdf 
found in some meteoric stones. 

• From X^^fitt\ 




I 



[ 265 J 



DIVISION VI. 

OF SOME SUBSTANCES THE NATURE OF WHICH 19 NOT 

YET CERTAINLY KNOWN. 

1. Preliminary Observations, 

X H£ bodies to be examined in this division have been arranged 
into a distinct class, because they present some extraordinary and 
anomalous results, and because as yet the knowledge obtained re- 
specting their nature is imperfect; many of the facts ascertained 
respecting them harmonize with the general doctrines of the science, 
and some of them offer new views respecting the arrangements and 
properties of matter ; they are therefore amongst the most interest- 
ing objects of chemical enquiry. 

2. Of the Fluoric Frinci/ile. 

1. There is a substance found abundantly in nature called Jluor 
sfiari it is usually either blue, green, yellow, or white, transpa- 
rent, and crystallized in cubes. It is a common product of the 
mines in Derbyshire. 

2. When this substance, in fine powder, is mixed with oil of 
vitriol and distilled in retorts of silver or lead, connected with re- 
covers of the same metal artificially cooled, an intensely active 
fluid is produced. It has the appearance of sulphuric acid, but is 
much more volatile, and sends off white fumes when exposed to air. 
It must be examined with great cauticm, for when applied to the 
skin it instantly disorganizes it, and produces very painful wounds. 
WhHf potassium is introduced into it, it acts with intense energy 
upon it) and produces hydrogene gas, and a neutral salt; when lime 

2 I. 



[ 266 ] 

is made to act upon it there is a violent heat produced^ water is 
given off, and tiie same substance as iluor spar is produced. When 
it is dropped into water a hissing noise is produced with much heat, 
and an acid fluid not disagreeable to the taste is formed if the water 
be in sufficient quantity. It instuiUy corrodes and dissolves glass. 

3. If, instead of being distilled in metallic vessels, the mixture of 
fluor spar and oil of vitriol be distilled in glass vessels, little of the 
corrosive liquid will be obtained ; but the glass will be acted upon, 
and a peculiar gaseous substance will be produced, which must be 
collected over mercury. The best mode of pracuring this gaseous 
body is to mix the fluor spar with powdered glass or powdered 
quartz, and in this case the retort may be preserved from corromon, 
and the gas obtained in greater quantities. This gas, which is called 
silicatedjiuoric gaoj is possessed of very extraordinary properties. 

It is very heavy; 100 cubical inches of it weigh 1 10.77 grains, 
and hence its specific gravity is to that of hydrogene nearly as 48 to 
1. When it is brought in contact with water it instantly depontsa 
white gelatinous substance, which is hydrat of silica, and the water 
becomes an acid solution of silica ; it produces white fumes when 
suffered to pass into the atmosphere. It is not affected by any of 
the common combusiiblc bodies, but when potassium is strongiy 
heated in it, it takes fire and bums with a deep red light ; the gas is 
absorbed, and a fawn-coloured substance is formed, which yields 
alkali to water with slight effervescence, and contains a combusti" 
ble body, and the washings afford potassa and a salt, from which the 
strong acid fluid mentioned in the last section may be procured by 
sulphuric acid. 

4. If instead of glass or silica the fluor spar be mixed with diy 
vitreous boracic acid, and distilled in a glass vessel with sulphuric 
acid, the proportions being one part boracic acid, two fluor spar, and 
12 oil of vitriol, the gaseous substance formed is of a different kind, 
and is called thefuoboric gas^ 100 cubical hiches of it weigh 73.5 
grains, so that its specific gravity is rather more than 32 times that 
of hydrogene. When a little of it is suffered to pass into the 
atmosphere it produces fumes nmch more dense than those produ- 
ced by the gas described in tiic last section, and which appear white, 

opaque. It is absorbed rapidly by water, and forms with 




r 

I 



[ 267 ] 

it a dense fluid like sulphuric acid In appeanmce and consistence; 
and when water is saturated with it at 50® Fahrenheit, it contains 
700 times its volume of gas, and is of specific gravity 1.77. When 
potassium is heated in this gas, it takes fire, and bums with a red 
light ; the gas is destroyed, if the metal be in sufficient quantity, and 
an olive-coloured substance is produced, which seems to be princi- 
pally boron, and a neutral salt, which, by the action of oil of vitrioly 
affords the dense fluoric acid, and sulphat of soda. 

5. It appears extrcinuly probable, fr6ni all the facts known re<* 
specting the fluoric combinations, that fluor spar contains a peculiar 
acid matter ; and that this acid matter is united to lime in the spar 
seems evident from the circumstance that gypsum, or sulphate of 
lime, is the residuum of the distillation of fluor spar and sulphuric 
acid : the results of experiments on the decomposition of fluor spar, 
have been differently stitcd by different chemists ; the maximum of 
sulphate of lime obtained from 100 grains in some experiments 
made in the laboratoiy of the Royal Institution, was 174.2 grains, 
and from this result fluor spar may be supposed to consist of 55 
lime, and about 20.7 fluoric acid, and this last number will represent 

the acid. 

6. The dense acid fluid described in 2, must, on the same idea$ be 
supposed to be a compound of an acid unknown in a separate state, 
and water ; and may be called hydrofluoric acid ; and supposing all 
the water in oil of vitriol transferred to it, it will consist of 20,7 flu- 
oric acid, and 17 water. 

7. The gas formed by the action of hydrosulphuric acid on a mix- 
ture containing silica and fluor spar, silicated fluoric gas, must be 
regarded as a kind of neutrosaline gaseous compound, consisting of 
fluoric acid and silica, and it has been found to afford, when decom- 
posed by solutions of ammonia, 6 1 .4 per cent, of silica ; it may there- 
fore be supposed to consist of two proportions of acid 41.4, and one 
of silica 61. According to this view of its composition, the number 
representing it is about 102; I volume of it condenses two volumes 
of ammonia, and they form together a peculiar saline substance 
-which is decomposed by water. The composition of this salt is 
eadly reconciled to the numbers above given, as representing silica 
and fluoric acid^ on the supposition that it contains one proportion of 



C 268 ] 

ammonia, and one of silicated fluoric acid ; and calculating the 
number of silicated fluoric acid on this supposition, it would be 
about 99. 

There is great reason to believe that, when potassium burns in 
this gas, it is the acid matter which is decomposed, and that it con- 
sists of oxygene united to an inflammable basis ; for if it were the 
silica alone which is decomposed, or if a mere combination were 
formed between the potassium and the acid gas, the same quantity 
of fluate of lime or fluor spar ought to be formed from equal quan- 
tities of silicated fluoric acid, acted upon by potassium, and after- 
wards exposed to solution of ammonia, and the other absorbed by 
water, and acted on by solution of ammonia ; which I have found is 
not the case, for in the first instance there is considerably less pro- 
duced. In tlie experiment, it seems likely that the potassium ac- 
quires oxygene principally from acid matter combined with the sili* 
ca, and that the inflammable basis of the acid partly combines with 
the potassa, and partly with tlie silica, or with silicum ; and forms 
with the first a compound that effervesces, and is partly decompo- 
sed by water ; and with the second an insoluble substance, which 
aflbrds silicated fluoric acid by absorption of oxygene. 

8. It is extremely likely that fluoboric acid gas is composed of 
the peculiar acid which is supposed to consist of oxygene and an in- 
flammable basis, and boracic acid ; but it appears that in the combus- 
tion of potassium in this gas it is the boracic acid alone that is de- 
composed, and that the fluoric acid combines with the potassa formed. 

9. It is a peculiar circumstance with respect to the fluoric prin- 
ciple, that silicated fluoric gas, and fluoboric gas combine witli bo- 
dies without decomposition. Thus they both fonn peculiar com- 
pounds with the alkalies ; and though silica is deposited by the ac- 
tion of silicated fluoric gas on water, and on other oxidated bodies, 
yet the new compound formed always appears to contain part of the 
eaith, which is supposed to Ije a constituent of the gas. In general, 
silica and boracic acid can only be procured from the two gasses by 
the imcrveiuion of bodies that contain water or oxygene : this cir- 
cumstance, if it were not opposed by the results of the experiments 
on the action of potassium on silicated fluoric gas, which, however, 
ought to be repeated, might lead to the suspicion, that the fluoric 



[ 269 ] 

gasses are compounds of a principle unknown in the separate state, 
but analogous to chlorine, with silicum and boron ; that the hydro- 
fluoric acid is a compound of the same principle with hydrogene 
and water, and fluor spar a compound of the same principle with 
calcium. 

10. If 20.7 be really the number representing fluoric acid, it can 
be supposed to contain only one proportion of oxygene, and the flu- 
oric basis will be represented by 5.7 ^ and it will be the only known 
acid so constituted. 

11. Silicated fluoric gas, when absorbed by water, aflbrds an acid 
fluid, which, when acted upon by ammonia, deposits silica ; and in 
glass vessels pure hydrofluoric acid cannot be obtained. Silicated 
fluoric gas seems to form only one combination with ammonia, 
which deposits silica by the action of water ; but fluoboric gas forms 
three combinations with ammonia, one volume of it condenses 1.2 
and 3 volumes of ammonia. The saline compound containing the 
least quantity of ammonia is solid, the other two compounds are 
fluids at the common temperature of the atmosphere. 

12. The only use to which the fluoric combinations have as yet 
been applied is for etching on glass ; for this purpose tlie hydrofluoric 
acid, or the fluate of ammonia, should be used ; the gasses have no 
action on glass. 

13. Silicated fluoric gas, and diluted hydrofluoric acid were disco- 
vered by Scheele, in 1771. Margraaf, three years before, had point- 
ed out some of the results of the action of acids on fluor spar ; con- 
centrated hydrofluoric acid and fluoboric gas were made known by 
some elaborate researches of Gay Lussac and Thenard, in 1809. 
My brother, Mr. John Davy, in 1810 and 181 1, extended the know- 
ledge of the properties of these bodies, and the modes of procuring 
them pure, ascertained the specific gravity of fluoboric and silicated 
fluoric gasses, and the proportions in their ammoniacal combinations. 
The action of potassium on silicated fluoric gas and fluoboric gas 
was investigated by M. M. Gay Lussac and Thenard, in 1809 ; and 
I made a number of experiments on the sajne subject about the 
same time. 



[ 270 ] 



3. Of the Amalgam firocured from ammoniacal ComfiountU. 

1 . When a globule of pure mercury is negatively electrified by a 
Voltaic apparatus of 100 pair of plates, it being in contact with lo- 
luuon of ammonia in a cavity made in a piece of muriate of ammo* 
nia, or any ammoniacal salt, moistened in such a manner, and so 
placed on a disc of platina, that the circuit is completed ; the glo- 
bule rapidly increases in volume, the quicksilver loses its fluidity} 
and at length becomes of the consistence of soft butter, and aibo- 
rescent crystallizations shoot from it, vt^hich are quite solid. The 
amalgam so formed has pcrfectiy metallic characters. It effervesces 
copiously when thrown into water, hydrogene ^as is given off, and 
a solution of ammonia is found in the water. When exposed to the 
air it gradually loses its consistence ; it emits a strong odour of am- 
monia, and reddens paper tinged with turmeric held above it ; and 
at last is found merely quicksilver. 

This curious experiment was made about the same dme by Dr. 
Zeebeck of Jena, and by M. M. Hissinger and Berzelius of Stock- 
holm, before the middle of the year 1 808 ; and they were led to 
make it in consequence of my experiments on potassa and soda. 

2. I found a still more easy mode of making the amalgam, by em- 
ploying mercury combined with a minute quantity of potassium, so- 
dium, or barium. When a compound of this kind is placed in con- 
tact with a solution of ammonia, or any moistened ammoniacal sah, 
it enlarges to eight or ten times its bulk, and becomes a soft solid, 
and may be preserved for a much longer time than the amalgam 
formed by electrical powers; it changes very slowly even under 
water. 

3. Different opinions have been foimed, and may still be formed, 
concerning the nature of this extraordinaiy substance. M. Berze- 
lius supposes that ammonia consists of a peculiar metal combined 
with oxygene, and of which metal hydrogene and azote are both pe- 
culiar oxides ; this idea was one that I started likewise soon after the 
disco vei7 of the amalgam. 

4. Another view of the subject is, that the amalgam consists of 
j^^^Br united to azote and hydrogene, the hydrogene being in 



y 



\ 



[ 271 ] 

larger proportion than in ammonia ; and this view has been embra- 
ced and defended by M. M. Gay Lussac and Tlienaixl ; but the sub* 
ject is still obscure and mysterious, and the true theory of the ex- 
periment can only be developed in consequence of new facts. 

5. Soon after the discovery of the amalgam, I attempted to pro- 
cure a peculiar metallic substance from it by distillation out of the 
contact of air, but without success ; whether I used the amalgam 
formed by electricity, or that procured by the intervention of the 
alkaline metals ; on the application of heat, hydrogenc and ammonia 
were always evolved, and the mercury recovered its former state. 
On the idea of the basis of ammonia being a peculiar metal, of which 
azote and hydrogene are oxides, these results can only be explained 
by supposing that the amalgam being formed from moist substances, 
sufficient water adheres to it to afford oxygene, and to produce tlie 
gaseous matter ; and the most perfect amalgam docs not yield a 
quantity of gaseous matter equal to more than -^hf ^^ ^^^ weight. 

I procured ammonia and hydrogene by heating the amalgam, how> 
ever, in cases in which it was carefully wiped with bibulous paper, 
and in which there was no appearance of adhering moisture ; and 
similar results have been obtained by M. M. Gay Lussac and Thc- 
nard. 

In the most accurate experiments, the proportions of ammonia 
and hydrogene were two to one in volume. 

6. There is no instance known of mercury retaining its metallic 
characters in combination with any other substance than a metal ; 
and it seems very probable that, if the matter existing in the amal- 
gam from ammonia could be procured in its perfect form, and could 
be exhibited as a solid under pressure, and at a very low tempera- 
ture, it would appear as an extremely light metallic substance. On 
the idea of its being a compound of azote and hydrogene, it will con- 
fflst of one proportion of azote 26, and 8 of hydrogene 8 ; and the 
number representing it will be 34. 

It is very difficult, but not however altogether impossible, to re- 
concile the idea of the substance in the amalgam being elementary, 
with analogies belonging to the general series of definite propol*tionl^ 
On such a supposition, azote must necessarily contain more than 
four times as much oxygene as hydrogene i and if 1 of basis to 



C 272 ] 

5 of oxygene, l>e supposed in hydrogene, then there will be 1 to 35 in 
azote, and 1 to 40 in nitrous oxide, 1 to 55 in nitrous gas, 1 to 85 in 
nitrous acid, and 1 to 15 in ammonia ; and 5, 15, 35, 40, 55, and 85, 
form a series of numbers having definite relations to each other. 

If the hypothesis of the elementary nature of the substance in the 
amalgam be adopted, water must be supposed to be constituted hj 
\ basis, and 50 of oxygene. 

It is extremely unlikely that such proportions should exist, and 
the general tenor of our knowledge of chemistry, as well as the re- 
sults of the experiments, render it much more probable that the 
amalgam is composed of quicksilver, azote, and hydrogcne. 



[ 273 ] 



DIVISION vn. 

ON THE ANALOGIES BETWEEN THE UNDECOMPOUNDED 
SUBSTANCES ; SPECULATIONS RESPECTING THEIH NA- 
TURE ; ON THE MODES OF SEPARATING THEM, AND 
ON THE RELATIONS OF THEIR COMPOUNDS. 

1 . Of the Analogies between the unde compounded Subitances ; IdcQs 

reajttfctinff their fiature. 

1 . X HE undecompounded substances most analogous to each otlier 
are certainly to be found amongst the metals ; some of these are so 
similar, that it requires refined observation, and sometimes experi* 
menty to distinguish them. There is likewise a chain of gradations 
of resemblance which may be traced throughout the whoU series of 
metallic bodies, at the same time that certain similnr and characte- 
ristic properties arc found to belong to metais in other respects most 
unlike each other. 

Silver and palladium, antimony and tellurium, agree in a great 
number of qualities. Potassium and platinum, if we except their 
lustre, colour, and power of conducting electricity, are bodies ex- 
tremely dissimilar; yet, by arranging the metals in the order of their 
natural resemblances, tliesc two substances may be made parts of 
one chain of natural bodies : potassium, sodium, and barium are 
very like each other ; barium approaches to manganesum, 2dnc, iron, 
tin, and antimony. Platinum is analogous to gold, silver, and palla- 
dium; and palladium is connected by distinct analogies with tin, 
zinc, iron, and manganesum. Arsenic and chromium, though 
amongst the most dissimilar of the metals in other respects, agree 
in the property of forming acid matter by combination with oxygene. 

2 M 



I 



C 2-* ] 

Amongst the inflammable bodies not metallic tliere are analogies, 
but iu>t a similar series. Sulphur and phosphorus agree in manjr 
rvspc^cws ; carbon and boron are likewise analogous, and are connected 
bv di!>unct relations with the metallic substances. Azote, whilst it 
a^re^rs with the other combustible bodies that have been named in 
fonuinc a;i acid by saturation with oxygene, is analogous to carboD 
in it* incapacity of uniting; to chlorine. 

Chlorine and oxy^'ne are separated from the inflammable bo&s 
by a number o£ marked distinctions ; yet sulphur agrees with chlo- 
rine in foniiini;: an acid by combining with hydrogene ; and has a 
weak attraction tor chlorine* and a strong attraction for metallic sub- 
stances. 

2. As far as our knowledge of the nature of compound bodies has 
extended, analogy of properties is connected with analogy of compo- 
^tion ; if one of the inflammable solids or metals is proved to be 
compound, there would be strong evidence for supposing; that the 
others were likewise compounded. It has been already mentioRed 
that sulphur and phosphorus, when Voltaic electrical sparks are 
taken in them In a state of fusion, afibrd hydrogene gas. I foaod, 
likewise, that \%h*?n :.n alloy of tellurium and potassium was acted 
upon by melted sulphur, telluretted and sulphuretted hydrogene 
equal to at least SO times the volume of the sulphur were disen- 
gaged. I ha\ c mide many experiments of this kind with similar 
results, the sulphur bcin^ recently sublimed in azote, and moisture 
being excluded with the greatest care. In the experiments of Vol- 
taic electrization, it might be supposed that the hydrogene being 
only in very small quantity might belong to an accidemal ad- 
mixture in the sulphur and the phosphorus ; but the proportion is 
too large in the experiments on the action of tellurium, potassium, 
and sulphur, to allow of a similar inference, and it seems more pro- 
bable that it arises either from the decomposition of the sulphur, or 
of the metals, or all of these bodies. 

3. We know nothing of the true elements belonging to nature; 
but as far as we can reason from the relations of the properties of 
tnatter^^^^j^rogene is the substance which approaches nearest to 
what ""^^ents may be supposed to be. It has energetic powers of 

parts are highly repulsive as to each other, and at- 



I 



[ 275 ] 

tractive of the particles of other matter ; it enters into combination 
in a quantity very much smaller than any other substance, and in this 
respect it is approached by no known body. 

After hydrog^cne, oxygene partakes most of the elementary charac- 
ter ; it has perhaps a greater energy of attraction, and next to hy- 
drogene is the body that enters into combination in the smallest pro- 
portion. 

4. I have already hinted at tlie idea that all inflammable matters 
may be similarly constituted, and may contain hydrogene. And on 
this supposition they may be conceived to owe their powers of com- 
bining both with oxygcne and chlorine, to the attractive energies of 
their combined hydrogene. 

On the most probable view of the nature of the amalgam from 
ammonia^'MS I have mentioned, it must be supposed to be compos- 
ed of hydikBlgene, azote, and quicksilver; and it may be regarded as 
a kind of type of the composition of the metals ; and by supposing 
them and the inflammable bodies different combinations of hydro- 
gene with another principle as yet unknown in the separate form, 
all the phenomena may be easily accounted for, and will be found in 
harmony with the theory of definite proportions. 

The metal of ammonia or ammonium must be supposed to be con- 
stituted by 8 of hydrogene, and 26 of azote ; and as azote unites to 
five proportions five times 1 5 of oxygene, it may be supposed to 
contain ten proportions of hydrogene ; and its constitution may be 
-thus expressed, 10 proportions of hydrogene and 16 proportions of 
an unknown basis. Ammonium, on the same hypotliesis, will con- 
sbt of 16 unknown basis, and 18 hydrogene. Potassium, the number 
representing which is 75 ; as it combines with 3 proportions of oxy- 
gene^ may be supposed to consist of 69 unknown basis, and 6 hy- 
drogene. Sodium, which is represented by 88, and which likewis<^ 
c:oinbines with three proportions of oxygene, may be considered as 
consisting of 82 basis, and 6 hydrogene. Tin, the number of which 
is 110, and which combines with two proportions of oxygene^ may be 
supposed to be consituted by 106 of basis and 4 hydrogene; and 
silver, which is represented by 205, of 203 of basis, and 2 hydro- 
gene. Amongst the acidifiable bodies, sulphur, which is represent- 
ed by 30, may be supposed to consist of 6 hydrogene, and 34 basis ; 



r 



[ ^76 3 

phosphorus of 4 hydrogene^ and 16 basis ; and charcoal of 4 hy- 
drogene and 7.4 basis. It will be unnecessary to supply any more 
of these estimations, the principles of which are obvious ; and in afr 
elementary book it would be improper to dwell upon matters of 
mere speculation ; even these transient views have been developed 
merely for the sake of pointing out a promising path of enquiry. 

5. In supposing the quantity of hydrogene in the inflammable 
solids and metals denoted by the quantity of oxygene or of chloriiie 
they absorb, it is taken fDr granted that the hydrogene forms only 
water or muriatic acid in the new combination, but it is possible 
that hydrogene may combine with oxygene and chlorine in many 
different proportions, and that its union with a peculiar bans msy 
Ihodify its power of attraction ; so that even allowing the general 
hypothesis, no confidence can be placed in the nwnerMb expres* 
siorts of the proportions of hydrogene and basis ; they tte offered 
merely as possible circumstances. 

6. The probabilities that the metals and inflammable solids may 
be constituted by different and various proportions of hydrogene and 
an unknown basis, are however strengthened, by the fact, that the 
metals in which hydrogene is supposed to be attracted by the largest 
quantity of other matter are the least disposed to combine with oxy- 
gene and chlorine ; and those that are supposed to contain the largest 
quantity of hydrogene to the smallest quantity of other matter, are 
the itibst combustible, and likewise those supposed to contain the 
largest and consequently the least attracted quantity of hydrogene, 
have the lowest specific gravity. 

7. When the analogy of the oxides to many of the hydrats, and 
that of the combinations of chlorine to many of the neutral salts, is 
considered, bodies so much alike tliat till lately they have been con- 
founded together ; the view that the inflammable bodies contain hy- 
drogene becomes still more likely. Water cannot be separated from 
the hydrats of potassa or soda by heat ; and the hydrat of lime is ex- 
tremely analogous to the pure earth ; and supposing the oxides to 
be compounds of unknown bases and water, it might be expected that 
the water would adhere to them with great energy, and would only 
be separated in consequence of the bases entering into a new com- 
bination. 



C 277 ] 

Common salt is very analogous to sulphat of potassa and other 
bodies known to consist of acid matter and alkaline matter; and if 
sodium consist of a basis combined M'ilh hydrogenc, then common 
salt may be considered as cumposcd of the same basis united to 
muriatic acid. 

8. Chlorine and oxygenc agree in many of their characters ; but 
the weight of chlorine, its colour, its absorbability by water, are all 
in favour of its being a compound. The number representing 
chlorine is so high that it may include four proportions of oxygene; 
and if this body be supposed to consist of oxygene united to an un- 
known basis, the analogy of the combinations of chlorine, both to 
the oxides and the salts, might be easily explained. The evidences 
in favour of such an idea of the constitution of chlorine arc, however, 
much inferior to those which render it probable that the inflammable 
solids contain hydrogone ; and this speculation on the composition 
of chlorine must not be confounded with the notion that chlorine is 
a compound of oxygene and muriatic acid free from water; for sup* 
posing a basis to exist in chlorine, it does not follow that it will be 
acid in its nature. The characteristic acid belonging to the combina- 
tions of chlorine is formed by the union of that body with hydrogcnc ; 
and sulphur likewise forms an acid by combining with hydrogene. 

9. I have mentioned, page 96, that in the electrization of a glo- 
bule of mercury in water, oxygenc appears to be combined with the 
metal, and yet no hydrogene evolved. I have made a number of 
experiments on this subject, and have ascertained that, in the process 
described, oxide is formed, without any apparent compensation in 
the production of inflammable matter ; nor was I able to detect any 
combination into which the hydrogene could have entered ; so tliat 
these experiments, as they now stand, would induce the belief that 
water is the ponderable basis of both oxygene and hydrogene, and 
that these two forms of matter owe their peculiar propcrt^f^either 
to the agency of imponderable substances, or to peculiar arrange- 
ments of the particles of the same matter ; but such a formidable 
conclusi(m as this must not be hastily adopted, for in all other cases 
oxygene and hydrogene appear as perfectly inconvertible substances, 
and in no other instance can one be procured from water without the 
correspondent quantity of the other, or without some product in 



[ 278 ] 

which the other may be supposed to enter. In all cases in which 
the circuit appears to be interrupted, even this is the case. When 
the finger is plunged in a glass of water connected with a wire rf 
platina positively electrified from the batteiy of 2000 double plates 
of the Royal Institution, oxygene is produced, and there is no ap- 
pearance of hydrogene ; but in this case the body is connected with 
a floor containing moisture, and at the extreme point of the mwst 
surface, where it is in contact with a metallic body, hydrogene must 
be disengaged ; and the same changes occur if a circuit be made 
through eight persons, their hands being in contact, the two forming 
the extremity of the chain having their fingers plunged in two 
glasses connected by wires of platinum with the two poles of the 
battery ; hydrogene is produced from one wire, and oxygene from 
the other. Till I ascertain that even acids and alkalies could be 
attracted from a central vessel in the Voltaic circuit to the two ex- 
tremities of the positive and negative metallic surfaces, it appeared 
very mysterious that oxygene and hydrogene should be separately 
produced in the Voltaic electrization of water ; but if it be possible 
for lime to be attracted through sulphuric acid to the negpative sur- 
&ce, it seems equally possible that hydrogene may be attracted 
through the moisture in a living body ; or a series of decompositioDS 
and recompositions may be simultaneously produced throughout the 
whole extent of the moist surface, by which, whilst a particle of 
oxygene is produced at one extremity of the chain, a particle of 
hydrogene is evolved at the other. 

10. There is, however, no impossibility in the supposition that the 
same ponderable matter m different electrical states, or in different 
arrangements, may constitute substances chemically different : there 
are parallel cases in the different states in which bodies are found, 
connected with their different relations to temperatui'c. Thus 
steam^ice, and water, are the same ponderable matter; and certain 
quantitiiS of ice and steam mixed together produce ice-cold water. 
Even if it should be ultimately found that oxygene and hydrogene 
are the same matter in different states of electricity, or that two or 
three elements in different proportions constitute all bodies, the 
great doctrines of chemistry, tlie theory of definite proportions, and 
tlie specific attractions of bodies must remain immutable j tlie causes 



[ 279 ] 

of the difference of form of the bodies supposed to be elementary-, 
if such a step were made, must be ascertained, and the only change 
in the science would be, that those substances now considered as 
primary elements must be considered as secondary ; but the num- 
bers representing them would be the same, and they would prol>ably 
be all found to be produced by the additions of multiples of some 
simple numbers or fractional parts. 

1 1 . That the forms of natural bodies may depend upon different 
arrangements of the same particles of matter has been a favourite 
hypothesis advanced in the earliest era of physical research, and 
often supported by the reasonings of tlic ablest philosophers. This 
sublime chemical speculation, sanctioned by the authority of Hooke, 
Newton, and Boscovich, must not be confounded with the ideas 
advanced by the alchemists concerning the convertibility of the 
elements into each other. The possible transmutation of metals has 
generally been reasoned upon, not as a philosophical research, but 
as an empirical process. Those who have asserted the actual pro- 
duction of the precious metals from other elements, or their decom* 
position, or who have defended the chimera of the philosopher's stone, 
have been either impostors, or men deluded by impostors. In this 
age of rational enquiry it will be useless to decry the practices of 
the adepts, or to caution the public against confounding the hypo* 
thetical views respecting the elements founded upon distinct analo- 
gies, with the dreams of alchemical visionaries, most of whom, as an 
author of the last century justly observed, professed an art without 
principles, the beginning of which was deceit, the progress delusion, 
and the end poverty. 

II. Of the Analogies between the Profierties of the firimary Com- 

fioundaj and on their Chemical Relations, 

1. In those compounds, which contain the same element com- 
bined with bases that resemble each other, a very great degree of 
sinodlarity might be expected ; and it is found that a number of se- 
condary combinations are still more analogous to each other than 
any of the undecompounded bodies. Ittria and glucina, baryta and 
strontia, potassa and soda are instances of bodies which, as to many 



C 280 3 

«tf their properties, might be mistaken for each other ; and a chaia 
of analogies may be traced through all the combinations of inflam- 
mable bodies and metals with chlorine, oxygene, and each other. 
All the adds, alkaline earths, alkalies, and combinations of chlorine 
in their pure states at common temperatures are nonconductors of 
electricity, by far the greater number possess a certain degree of 
transparency; in their combinations with each other they display 
analogous results ; most of them form hydrats ; they render solid a 
certain quantity of water, and arc usually dissolved by a greater 
quantity ; and even acids combine with each other in consequence 
of the intermedium of water, as is the case with the sulphureous and 
nitrous acid gasses. 

Libavius's liquor, or stannanea, is a limpid fluid ; if mixed with 
a certain proportion of water it becomes a solid crystalline body. 
The glacial oil of vitriol, and the hydrophosphorous acid are instances 
of oxidated bodies forming crystalline solids with water. 

2. The eartlis and the oxides which are insoluble in water still 
condense a certain quantity of thb fluid, and it gives a greater fuu- 
bility to those which retain it with sufRcient energy to be submitted 
to a strong heat. All oxides and earths obtained by precipitattoik 
from aqueous solution, that I have exanuned, are hydrats, and such 
of them as I have carefully analyzed, I find contain the water in de- 
finite proportions. The combination of an earth, an alkali, or an 
oxide with water may be considered as amongst its weakest combi- 
nations, for the water is expelled by carbonic acid. The expulsion 
of water from the earths seems to be connected, as I stated in page 
41, with the contraction of volume, which many of them undergo bj 
ignition : the particles, wlien the water is driven off, approach nearer 
to each other, and a great contraction is the i*esult, and probably 
sometimes a semi-fusion. This quality on which, as it has been 
stated, the pyrometer of Wedgwood is founded, b elegantly exem- 
plified in an experiment I have lately made on the hydrat of zirco- 
na. When this body is heated, at the moment of the expulsion of 
the water, there is so great and rapid a contraction of the particles 
of the earth, that they become incandescent in the process ; and, 
from its being as soft as resin, become sufficiently hard to scratch 
rock crystal. 




[ 281 ] 

3. In general those compounds of oxyg;cney t]ic bases of whicli 
conibine with most energy, likewise exert the greatest force of at- 
traction on each other ; such, for instance, arc the metals of the fix- 
ed alkalies in their i*elations to sulphur, phosphorus, arsenic, and 
tellurium ; and potassa and soda readily combine with the acids of 
sulphur, phosphorus, and arsenic, and with the oxide of tellurium. 

4. No refined experiments huvc as yet been made on the mutual 
action of these compounds of chlorine and oxygene, whicli are capa- 
ble of co-existing ; but the salts called hyperoxymuriutes arc sub- 
stances in which clorine and oxygene exist combuied with metals ; 
and the facility with which they are decomposed depends upon the 
tendency of the metal to unite to chlorine, so as to form a binary 
compound, a circumstance connected with the expulsion of the oxy- 
gene. The hyperoxymuriate of potassa; when it was first formed 
by Dr. Higgins, was supposed by him to be a species of nitre, from 
the similarity of its obvious properties : and it is remarkable that 
its composition is the same as that of nitre, except that in the first 
salt there is a proportion of chlorine, and in the second one of azote. 
Hyperoxymuriate of potassa consists of 1 proportion of potassium 
75y 6 of oxygene 90, and 1 of chlorine 67. Nitre consists of 1 of 
potassium 75, 6 of oxygene 90, and 1 of azote 26. The combina- 
tions of anmionia with the compounds of chlorine, offer a class of 
curious bodies to the chemical enquirer, the properties of which 
have never been investigated : that formed by phosphoiiuia, and re- 
ferred to page 165, is a most extraordinary substance, and its ele- 
ments are combined with a degree of energy which renders it analo- 
g^ous to a primary compound. 

5. In the combinations of ammonia with acids and oxides, the hy- 
drogene of the ammonia is always in some definite proportion to the 
oxygene of the acid or oxide, so that water may be formed by the 
decomposition of the compound ; this is obvious from the dccom- 
posiUon of the fulminating ammoniacal metallic compounds. If a 
solution of ammonia be poured into a solution of gold, a brown pow- 
der falls down, which, when washed and dried, explodes by a gentle 
heat. I caused it to detonate in small quantities in exhausted glass 
retorts, and I found that the products were water, azote, and gold 



[ 282 3 

Fulminating silver is a compound in which the elements seem to 
be in similar relations to each other ; it was discovered by M. Ber- 
thoUet) and may be made by dissolving the oxide of silver, procured 
from the nitrous soludon by lime water in solution of ammoma at 
common temperatures, and exposing the mixture to spontaneoas 
evaporation; black crystals form^ which must be examined with 
great caution, and only in small quantities, as they explode by the 
mere contact of a soft body. 

6. The extensive class of bodies called neutral salts are formed 
by the mutual action of acids, and oxides, alkalies, and earths; and 
in general those oxidated bodies that contam least oxygene, are such 
as most readily enter into combination with acids ; thus the perox- 
ides generally are either insoluble in acids, or require the abstraction 
of a portion of oxygene to become soluble ; and in general two in- 
flammable bodies in combining with oxygene, unite to less than the 
added sums of the quantity they would separately combine with to 
saturation. Many of the neutral salts may be considered either as 
combinations of peroxides with inflammable bases or as alkalies 
united to acids, or as peroxides united to oxides ; for instance, the 
compound formed from sulphureous acid gas and potassa -consists of 
potassium and sulphur, with three proportions of oxyg^e, and may 
be regarded as a compound of peroxide of potassium and sulphur. 
Sulphate of potassa contains four proportions of oxygene, and might 
be regarded as a compound of peroxide of potassium, and oxide of 
sulphur. They are in fact all compounds of oxygene with double 
bases ; and when one fixed alkali, or earth, or oxide, separates ano- 
ther, it may be supposed that the basis only is changed : thus, where 
hydrat of potassa separates lime from its nitric solution, it may be 
conceived that the potassium only takes the place of calcium ; and 
that the oxygene and water of the hydrat of potassa unite to this 
metal, and that the potassium unites to the oxygene, nitrous acid, 
and water of the solution. 

7. It is very easy to estimate the composition of any of the com- 
binations of alkalies, earths, or oxides with acids, by adding together 
the numbers representing their elements ; thus sulphate of soda is 

d of 60 sulphur, 90 oxygene, which make two proportions 
uric acid; and 88 of sodium, and 30 of oxygene, whicli 




[ 283 ] 

make one proportion of soda. Carbonate of lead is composed of two 
pi'oportions of carbonic acid, equal to 82.8, two proportions of oxy- 
gene 30, and one of lead 398. Sulphate of lead is composed of two 
proportions of sulphuric acid 150, two of oxygene 30, and one of 
lead 398 : sulphate of nickel of two proportions of sulphuric acid 
150, and one of oxide of nickel 141 ; and these proportions ag^ree al- 
most precisely with the best analysis. 

8. It appears that in tlie neutrosaline compounds in which there 
is a perfect harmony between the proportions of the elements, the 
result is neutralization ; and in this case a crystalline compound, or an 
insoluble compound is usually formed. Thus in the instances above 
mentioned, in the sulphates of soda and lead ; the sulphur is a binary 
proporUon, and the oxygenc a binary proportion, or a multiple of a 
binary proportion ; and in tiie carbonate of lead, the carbon b a bi- 
nary proportion, and the oxygenc a multiple of a binary proportion ; 
and to give another instance, in the sulphate of barytcs the sulphur is 
a single proportion, and the oxygenc a single proportion, or a mul- 
tiple. 

When, on the contrary, there is a want of harmony in the propor- 
tions, the excess either of acid or basis seems to be shewn in the 
properties of the result ; and it is seldom a crystallized body. Thus 
in the soluble red sulphate of iron, the number of proportions of oxy- 
gene in the oxide arc three, and those of the sulphur in the acid 
are four: and this body is strongly acid and uncrystallizable. 

HI. 071 the relative jittractions qf the undecom/ioaed Substances for 

each other, 

1 . The attractions of the undecompounded substances vary with 
the temperature, probably, chiefly in consequence of their different 
degrees of volatility ; for although freedom of motion in the parts of 
bodies wonderfully promotes combination, yet the disposition in bo- 
dies to assume the aeriform state at high temperatures, enables de- 
compositions to take place in an order which would not be expected 
from the known agencies of the substances under common circum- 
Mances. 



C 284 ] 

3. The bodies that follow are arranged in the order of their attrac- 
tions for oxygene^ at the lowest temperature of visible ignition^ after 
the results of my own observations. Potassium, sodiumi, barium, 
boron, carbon, manganesum, zinc, iron, tin, phosphorus, antimonjr, 
bismuth, lead, sulphur, arsenic, tungstenum, azote, palladium, mer- 
cury, silver, gold, platinum. 

3. The attractions of bodies for chlorine follow an order very dif- 
ferent, though with some exceptions ; potassium, sodium, zinc, iron, 
lead, silver, antimony, bismuth, phosphorus, copper, sulphur, mer- 
cury, platinum, gold. 

4. The attractions of the undecompounded bodies for sulphur 
have not been determined to any extent. Potassium and sodium 
seem to have the highest attraction of any substances : then iron, 
copper, antimony, palladium, lead, and silver. 

5. No bodies combine with phosphorus with more energy than 
the metals of the fixed alkalies : and after them platinum, zinc, anti- 
mony, and sulphur, appear to have the strongest attractions ; but no 
very definite knowledge has been as yet obtained on the relations of 
the phospburets. 

6. The general phaenomena of the decomposition of the binary 
compounds, by undecompounded bodies, can require no illustration. 
Potassium separates chlorine and oxygene from all known bodies; 
usually it produces potassa, but sometimes by acting on compounds 
containing abundance of oxygene, it forms the peroxide of potassium. 
Carbon, in reducing metallic oxides, forms either carbonic acid, or 
gaseous oxide of carbon, according as the oxygene is more or less 
strongly attracted by the basis. When oxides are decomposed by 
sulphur, sulphureous gas and sulphurets are almost always formed. 

7. Some of the instances which were formerly supposed instances 
of single attractions are now known to be connected with double at- 
tractions. This is remarkably the case in the production of potas- 
sium by iron. The water m the hydrat of potassa and the potassa 
seem to be decomposed at the same time ; the iron unites to the oxy- 
gene of both ; the hydrogene and potassa combine ; and their ga- 
seous compound deposits potassium on cooling. 




[ 285 3 



IV. On the Methods qf ^efiarating the undecom/ioeed Bodies from 

each other, 

1. General methods of separating the undecompounded bodies 
from each other may be learnt from a consideration of the processes 
by which they are procured; but there arc other modes which ap» 
ply to many of their compounds, and which are still more simple. 

3. As all the undecomposed bodies differ in the manner in which 
they are affected by heat, many of them may be separated from com- 
pounds, by exposing them to different temperatures. Thus oxygcne, 
chlorincy mercury, phosphorus, and sulphur may be detached from 
many bodies by the process of ignition. 

3. In most cases, however, complicated methods are necessary, 
particularly in cases when the bodies are united to oxygcne and acids 
or to chlorine ; the compounds of chlorine differ very much in vola- 
tility, and in cases when they arc mixed together, they appear to act 
upon each other with very little energy only: hence, if it is possible 
to combine all the elements of a compound with chlorine, by the ac- 
tion of the gas, or of muriatic acid, or nitro-muriatic acid, they 
may be easily separated by the application of a heat gradually in- 
creased. Amongst the metallic combinations, tliat of tin when sa- 
turated with chlorine rises first, then those of arsenic, antimony, 
tellurium, iron, zinc, bismuth, in the order in which they have been 
named. 

Silver is easily separated from solutions in which it exists by mu- 
riatic acid, with the chlorine of which it forms an insoluble com- 
pound ; and in the same way chlorine is separated, and its quantity 
in any substance ascertained by means of solution of silver. 

Oxide of iron is separated from solutions by succinate of ammonia, 
with which it forms an insoluble salt. The oxides of copper, nickel, 
and cobalt, are all soluble in ammonia. Those of zinc, tellurium, 
tin, and. platinum, in solution of potassa. Acids are separated by al- 
kalies ; and alumina, silica, zircona, ittria, glucina, and the alkaline 
earths, may with facility be detached from their combinations by the 
action of acids, alkalies, and carbonates. Oxide of lead and baryta 



[ 286 ] 

may be easily beparated from other bodies, iii consequence of their 
forming insoluble compounds with sulphuiic acid. 

4. The order in which metals precipitate each other from solu- 
tions, is nearly in the ratio of their attraction for oxygcne ; and in all 
cases of neutral compounds, the precipitating metal takes the oxy- 
gene and acid of the metal thrown down. Iron readily precipitates 
copper ; zinc readily throws down tin, lead, tellurium, bismuth, &c. 
and in general the metallic substances, as has been stated page 83, 
attract oxygene, and precipitate each other in a ratio connected with 
their electrical relations; those that arc positive with respect to others 
having the highest attractive powers for oxygene and acids. 

By Volatic electricity all substances are separated from their 
compounds with oxygene and chlorine ; or alkalies, earths^ and ox- 
ides are separated from acids, as has been mentioned page 90, and 
that in an uniform order and in definite proportions, so that Voltaic 
electricity offers general methods of decomposing all compounds 
soluble in water; and for most experiments of this kind very small 
combinations only arc necessary : if small quantities of the materials 
are employed, two or three double plates are sufficient for decompos- 
ing most metallic solutions. The energies of small powers in acting 
upon bodies by diminishing the quantities exposed to their agency^ 
has been happily shewn by Dr. Wollaston, in the decomposiuon of 
water by a common small electrical machine, by passing the elec- 
tricity from surfaces of about the j^ins ^^ ^ square inch ; and the 
siame philosopher has produced the ignition of platinum in leaf oi-^^ 
of an inch in thickness, by a single series of double metals of a few 
inches square : the zmc is circular, forming a small hollow tube, 
iind surrounded by copper opposed to each side of it, and bent so as to 
correspond to the form of the zinc ; when the two metals are ex- 
posed to the action of an acid, and connected by the leaf of platinum, 
the effect is produced. 

V. General Observations^ and Conclusion of Part First. 

\i the imdecompounded bodies, or even of the primary 

coir ■ ^ as is evident from what has been said, are found in an 

state on our globe; their tendency to unite with each 




[ 287 ] 

Other 18 constantly exerted ; and a scries of decompositions and re- 
combinations arc constantly occurring in the phenomena of nature, 
and in the operations of art. The compounds containing more than 
two elements, will form the subjects of consideration for the second 
part of this work, and their arrangements in the mineral, vegetable, 
and animal kingdoms : when the principles that have been advanced 
in the preceding pages, will be applied to the elucidation of an im- 
portant series of changes belonging to inorganic and to organic 
matter. As far as our investigations have extended, the same ele- 
ments belong to the same parts of the system. The composi- 
tion of the atmosphere and the ocean are analogous, as far as the 
heights of one, and the depths of the other have been examined. 
The matters thrown out by volcanoes arc earthy or stony aggregatcsi 
and they may owe their origin to the action of air and water upon 
the metallic bases of the earths and alkalies; an action which 
may be supposed to be connected with the production of subterrane- 
ous fires. Even the substances that fall from meteors, though dif- 
fering in their form and appearance from any of the bodies belong- 
ing to our earth, yet contain well-known elements, silica, magnesia, 
sulphur, and the two magnetic metals, iron and nickel. 

2. A few undecompounded bodies, which may perhaps ultimate- 
ly be resolved into still fewer elements, or which may be different 
forms of the same material, constitute the whole of our tangible 
universe of things. By experiment they arc discovered even in the 
most complicated arrangements ; and experiment is as it were the 
chain that binds down the Proteus of nature, and obliges it to con- 
fess its real form and divine origin. 

The laws which govern the phaenomcna of chemistry, produce in- 
variable results ; which may be made the guide of operations in the 
arts ; and which insure the uniformity of the system of nature, the 
arrangements of which are marked by creative intelligence, and 
made constantly subscrv^ient to the production of life, and the in- 
crease of happiness. 




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[ 291 ] 



To face Plate IX. 

The opposite plate represents an apparatus for minute cxpeiiments; 
the instruments are delineated of their real size. The cups should 
be of platinum, the tubes and small retorts of glass ; the blow pipe 
may be of silver, with an extremity of platinum^ By the help of 
these instruments, and a little wooden trough holding a few pounds 
of mercury, an electrophorus for giving a spark to act upon mix- 
tures of gasses, or compound glasses ; and a few bottles c<aitaining 
acids, alkalies, and precipitants, a number of useful experiments may 
be made. Boxes containing the apparatus on a very small scale, are 
neatly made, and sold at reasonable prices, by Mr. Newman, 10, Old 
Lisle-street, London. 



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C 293 3 



To fact Plate X^ 

Tbk opposite plate represents a Gasometer, by which a stream 
of oxygene gas may be throWki upon ignited charcoal} for the 
purpose of fusiDg or buming bodies^ ficc 



#• 



APPENDIX. 



Since the last sheet has been sent to the press, M. Berzelius has 
had the goodness to communicate to me the following estimates, 
some of which agree very nearly with those given in the preceding 
pages ; others are new, and all afford evidences of the truth of the 
theory of definite proportions. It is peculiarly satisfactory to me, to 
be ablelMkate the coincidence of so many of the conclusions of this 
distinguished chemist with my own results, obtained usually by very 
difierent methods of operation. 



Of the Oxidea of Antimony, 



First Oxide 
Second 
Third 
Fourth 



Metal. 
100 



Ozygene. 

4,65 
18,6 
27,9 
37,2 



MetaL 
96,826 
84,S17 
78,19 
72,85 



Oxygene. 

3,174" 
15,683 
21,81 
27,15 



Metil. 
88,03 
83,13 
78,61 



Oxygene. 
11,97 
16,87 
21,39 






The Sulfihuret qf Antimony ^ is composed of 100 parts of Metal, 
;and of 37,25 parts of Sulphur. 

Oxides qf TYn, 

Metal. Oxygene. 
First 100 13,6 

Second — 20,4 

Third — 27,2 

The Sulfihureta of Tin. 

Metal. Oxygene. Metal. Oxygene. 

First 100 27,234 78,6 21,4 

Second — 40,851 71,8 28,2 

Thisd — 34,468 

The Oxide of Tellurium, 
100 parts of Metal with 24,83 parts of Oxygene, 

Telluretted Hydrogcne, 
Tellurium 100 pHtSs. Hydrogene 1,948. 



h 



I 



296 


APPCNIJIX. 
The Oxidee af Gold. 


^ 


1 • 

I First 

r Second 


Metal. Oin:«>e' MenJ. 


Oxreeae. 


100 11,026 96,13 


3,87 I 1 
10,7755 3 


— 12,077 89,233 


• 


The Oxides ofPlatlmivi. 






MetaL Oiygene. MttaL 


OxTgena 


First 


100 8,287 93,35 


r,65 ? 1 
14,1 5 3 


. Second 


— 16,574 85,9 


1 


The Oxide of Palladium. 




[ ' 


MetaJ 100. Oxygene U,0S5. 




t 


Sulfihuret 0/ Palladium. 






Metal 100. Sulphur 28,15. 






The Qxidet of Manganesum. 






MetsL Oijgene. Metal. 


<*»-■ 


First 


100 7,0366 93,435 


6,S65T 


Sccoml 


— 14,0533 87,68 


13,32 S 


Third 


— 28,1077 78,1 


21,9 L* 


Fourtli 


— 42,16 72,35 


27,75 6 


f Fifth 


— 56,215 64 


36 J 8 




etallic Oxides examined by other Swedish Chemists. ^^ 




Oxidei qfMtrcmy, by M. Sefctrom. 


,95) 1 ■ 







Oxide of Bitmuth, by M. dc Lagerhielm. 
Metal 100. Oxygene ll^rs 
Oxide of Mckel, hy M. de Rolhoff. 
First, Metal 100. Oxygene 27,3 ? T 
Second, — . 40,95 $ 1^ 

Oxide of Cobalt, by the same. 
^ First, MeUl lOO. 



• 



First, Meul loO. Oxygene 27,3 ) 1 • 
Second, 40,95 5 1^ 

Oxide qf Cerium, by M. de Hianger. 
First, Metal 100. Oxygene 17,41 > 1 
Second, . 36,1155 i|'T^ 



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THE NEW YORK PUBLIC LIBRARY 
REFERENCH DEPARTMENT 

This book ia uadcr do circumstauees to be 
taken from the Buildiatf 






















































































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